Potato beetles showed up in my garden this year, and I was ready- here’s what I did to get rid of them organically and naturally without harmful pesticides… and it actually worked!
Did you know that potatoes are on the Environmental Working Group’s “Dirty Dozen?” This is the top twelve produce items with the most pesticide residue on them- the ones you should always try to find organic. We like to keep a good stockpile of potatoes for fall and winter (because french fries), so growing them ourselves successfully without harmful chemicals is important to us!
When I was a little girl I had a bug collection. I was a full-on geek bug collector with styrofoam and bugs with needles pinned on it and everything. Now I’m in my thirties and loathe the little things. Not sure what happened there… I used to willingly touch them, but now I thrash and scream when one lands on me.
Perhaps my least favorite bug is the Colorado Potato Beetle, and that is because last year they absolutely decimated my prized potato plants and left us with but a meager potato harvest. Plus their larva are so very gross-looking. Disgusting. The things that nightmares are made of.
One day I walked out to the garden to find the plants covered with adult potato bugs, eggs, and every stage of larva in between. It was like a scene from one of those infomercials where they tell you we’re destroying the rainforest at an alarming rate and show clear cut trees with excavators and bull dozers running all around… except in my potato patch.
Well not this year! I WILL be eating homegrown potatoes! Basil Butter Roasted Potatoes? Yes!!
Here’s what I’ve done to win against potato bugs naturally, organically, without harmful chemicals, and without a ton of labor. A little bit of labor, but not unreasonable.
Be Proactive and Be Prepared
From the time your potato plants come up, take a couple minutes every other day to walk the rows and scan for adult potato bugs and watch for holes eaten out of the potato leaves. It’s infinitely easier to control potato bugs if you can catch them when they first appear. I lost my crop last year because I wasn’t paying attention and was blind-sided. Plus I didn’t realize just how much damage they could do.
Controlling potato bugs involves three main steps: physically getting rid of the adult beetles, removing leaves with unhatched eggs, and using an organic bug killer to kill any baby potato bugs that hatch.
Understanding Potato Bugs
If you’re going to kill something, its nice to at least know a little bit about it and also about what you’re using to kill it. Running to the hardware store and buying the first bottle of whatever bug spray you see that will supposedly kill potato bugs isn’t good gardening practice. Understanding just a little bit of bug biology and behavior takes the mystery out of things and makes them so much easier to treat for. Using this information, we can naturally and organically control them, without the use of heavy pesticides.
I See a Potato Bug, Now What?
Game on. Initiate Potato Bug Control Plan. By the time you see one adult potato bug, there are probably more and they’ve probably already laid eggs.
Adult potato bugs overwinter in the ground, and when temperatures warm in spring they climb their way out of the earth and find the first potato or other nightshade family member they can. When do potato bugs first appear? About the same time potato plants sprout and emerge from the ground. Naturally. As soon as your potatoes are up, start watch.
How to Remove and Kill Adult Potato Bugs
I wear gloves because potato bugs gross me out. If there are a lot of them, things will go quicker if you carry a tin can of soapy water to throw them into. Just pluck them off and drop them in. Karl has many memories of helping his grandparents pick potato bugs off rows and rows of plants and putting them into a tin can filled with gasoline.
If there aren’t many I just pick them off and squish them real good with a nearby rock or stick. And then I wave my finger in the air and shout, “let that be a lesson to you all.” This step will definitely help with the control of your potato bugs.
Searching for adult potato bugs is something I do almost every single day, sometimes multiple times per day in the first couple weeks once they’ve showed up for the year. They are large and easy to see- it’s super quick to do, doesn’t require bending over, and will save a lot of time and effort later since one potato bug can lay 300-800 eggs in her lifetime over a couple weeks.
This is a good time to point out that these methods are geared towards the home gardener or homesteader with a moderate potato crop. To give you an idea of what we were able to successfully handle with no problem… we have around 160 potato plants this year.
Look for and Destroy Potato Bug Eggs
Once you’ve removed the adults potato beetles, the second step is to immediately go after the eggs. This is especially important in the beginning. Potato bug eggs can hatch in as little as 4-5 days, and we want to nip them in the bud!
I think that doing this made an incredible difference!
You will find the eggs on the underside of the potato leaves. I look for them by using my hand to gently push the potato plant over in each direction, exposing as much of the underside of the leaves as possible. The eggs are bright blaze orange against the green of the leaves, so they will easily catch your eye. Make sure to check all of the leaves, even the small ones and also the ones really close to the ground.
When you find a leaf with a cluster of eggs, pick that leaf off and throw it in your tin can. Every leaf you find with eggs is potentially saving you a lot of work down the road!
The cluster of orange are newly laid eggs, the cluster of black is a patch of newly hatched eggs!
As long as I am still finding adult potato bugs, I still check for eggs. I had good success in checking for eggs every day for the first few days that the potato bugs showed up, and then every two or three days after that until I stopped finding adult potato bugs. It is more time consuming and harder work than just scouting for the adults, but its ultra-satisfying to find and eliminate a leaf with dozens of eggs on it!
Once I stopped seeing adults, I stopped looking for eggs. For me this was two or three weeks after the first adult potato beetles arrived.
How to Kill Potato Bug Larva
Inevitably you won’t catch all of the eggs, and some will hatch and turn into little potato plant munching machines. And these, these are the things that will actually destroy your plants- they’re small, but they’re voracious!
Don’t panic, it’s okay if this happens. It WILL happen.
Once they hatch, the larva will go through four different instars, which is the fancy name for developmental stages. They start off as itty bitty black and orange pin-head sized bugs, and turn into the most disgusting grub-like things. Oh how I hate grubs.
The itty bitties always seem to start out in the central area on the leaves they hatched from… which is kinda nice because they are all in one area. Every day they grow, they spread out a little bit more.
If you don’t catch them and they are allowed to get to their last developmental stage (in about 2-3 weeks) they will drop off the plant, burrow into the ground, and emerge as an adult potato beetle in 5-10 days to start the cycle all over again and fill your plants with eggs. Obviously we want to prevent this at all costs.
Organic Treatment for Potato Bugs
The bad news is that there aren’t a lot of organic and natural products that will kill adult potato beetles- they are notoriously hard to get rid of.
The good news is that the larva are much more susceptible to the organic products we have available, and we can definitely get rid of the bulk of their population.
This is the main reason why the combination of techniques- picking off the adults, scouting for eggs, and then treating the larva is the most effective solution.
So what are natural and organic products that kill potato bug larva?
The following section updated for 2019!
I’m starting with Diatomaceous Earth because it one of my favorite tools for controlling potato bug larva. This stuff works really well, especially for smaller larva, and it is incredibly easy to use- no mixing with water, no sprayers required, and you can use it safely any time of the day. The first time I used it I saw hash, potato soup, and french fries in my future.
What is it? The fossilized remains of a type of hard-shelled algae.
How does it work? By disrupting the exoskeleton, and causing the potato bug larva to dehydrate and die.
How do you use it? It’s a fine powder that is dusted directly onto the larva and leaves.
Other things to know about using Diatomaceous Earth:
It will kill many types of bugs, including good guys like lady bugs and bees. Bees are only interested in the flowers though, and potato bugs really aren’t, so the actual danger to bees is very minimal if you only dust the larva and leaves.
Diatomaceous Earth can be dangerous if inhaled. You don’t have to wear a mask or anything… just don’t snort it and be cautious if there are strong wind gusts.
It is only effective when dry. This means that you’ll have to wait to apply it after any dew dries, and you’ll need to be mindful of rain in the forecast- don’t apply it immediately before it rains or you’re just wasting your time.
It covers the leaves, preventing photosynthesis where you put it. Use Diatomaceous Earth– only where you see little potato bug larva. Do not use this preemptively or on plants that are not infested. The good news is that the wind and dew and rain will wash most of it off after a couple days. And the bugs will be dead at this time also, so that works out well for the plant’s sake.
In my experience, this killed the potato bug larva in less than a day and was quite effective. Sprinkle it on the bugs one day, and they have disappeared by the next! This will only work on the potato bug larva that get directly hit with it- sometimes they can be hiding under a leaf or in a place that the powder doesn’t reach, in which case they’ll escape death… this time.
Where do you buy Diatomaceous Earth?
Some farm stores will carry it, otherwise this brand is the best value I’ve found online. Just make sure you get one that is “food grade.”
For ease of use, I put the Diatomaceous earth into a standard-size used spice bottle for sprinkling- this worked wonderfully. Any larger vessel and I think it would have distributed too much at one time.
I also tried Neem Oil, and while it seemed to work okay, it wasn’t as convenient for me personally, although I know it is one of the top products that other people swear by for killing potato beetles.
What is it? Oil pressed from the fruits and seeds of the Neem tree.
How does it work? It disrupts things related to hormones like ability to eat and reproduce.
How do you use it? Spray on the leaves of the plant- the bugs need to eat it for it to work.
Other things to know about using Neem Oil:
The most important thing: get the right kind of Neem Oil and KNOW what you’re getting! I can’t stress this enough. The Neem oil you find in the gardening section of your hardware store is probably not the correct kind, unless you have a super awesome hardware store run by hippies.
Neem is too general of a term. When Neem is processed it turns into two main things: Azadirachtin and Clarified Hydrophobic Extract of Neem Oil (also sometimes referred to simply as “Neem Oil”).
Azadirachtin is what we want- it has the most bug-killing properties. Hydrophobic Extract of Neem Oil kills some bugs, but not as well and in the case of potato bug larva, possibly not at all. If you’ve tried Neem before and it hasn’t worked, it might be because you had the wrong kind.
So which Neem should you get and where can you find it? Get REAL, potent, potato bug-killing Neem Oil here.
There is a lot of information on the different mechanisms of how Neem Oil kills or deters bugs. Some report that it simply repels them, some say that it disrupts their hormones and causes them not to eat and they starve after a couple days, and some say it prevents them from reproducing. Whatever it is, it isn’t necessarily instantaneous.
It degrades quickly. Azadirachtin has a very short half life: 48 minutes to 4 hours in water, and around 2 days on a leaf’s surface. This is why the good stuff is sold as a concentrated oil that you mix yourself. If you plan to use Neem Oil, you will need to predict how much you’ll use, and make a new batch for every spraying session.
It can burn your plants if you mix it too strongly, or apply it in the middle of the day or in the hot, direct sun. Neem Oil is best applied early in the morning, or in the evening. And just make sure you follow the mixing instructions on the package. You’ll need a spray bottle for applying it too, by the way.
Where do you buy REAL Neem Oil?
You’ll probably have to pick this one up online, find the good stuff here.
As of 2018, Spinosad is my new favorite organic product for killing potato bug larva! We finally tried it, and wow was it a life-changer!
This is perfect for the situations in which you’ve missed a leaf with eggs, the eggs have hatched, and now there are hundreds of tiny larva all over the plant. One dousing with Spinosad and they are gone, often within hours! Miraculous!
This also works if you’re even farther down the line and the larva are quite large. I think that Spinosad works better on larger larva than then the Diatomaceous earth does.
What is it? A fermented substance produced by certain bacteria found in the soil
How does it work? It affects the nervous system of insects that eat or touch it.
How do you use it? As a spray on the leaves of the plant.
Other things to know about using Spinosad:
While it can be toxic to insects when they simply come in contact with it, the toxicity is low once it has dried. It is much more toxic to insects that eat it. It will be toxic to bees when wet and up to about 3 hours after first sprayed, so only spray when beneficial insects aren’t around, usually early in the morning or late evening. It is safest to use when the potato plants are not flowering.
Many of the popular Spinosad sprays available also come with a list of limitations broken down by fruit or vegetable type- things like the number of days between applications, how many times you can use it in one season, and how long you have to wait to harvest after spraying. Might want to read these if you end up using it a lot. Because of this, consider alternating it with one of the other products I’ve mentioned.
It is recommended to only mix as much as you will use in a single treatment.
There were no specific instructions for what time of day to use Spinosad, but since it is mixed with water you will want to avoid spraying in the heat of the day to avoid burning the leaves of your plants.
I believe that Spinosad is longer lasting and may be a good choice for someone who can’t dedicate a little bit of time every three days to potato bug duty. This would be my first choice if I walked into the potato patch and it was highly infested with tons of large larva (similar to potato devastation picture above). I wish I had known about this during the epic infestation of 2017- it probably would have save my potato harvest that year.
Where do you buy Spinosad?
There are several different brands that make this- you may find one at your local hardware store, or you can find it online here for a reasonable price.
My two best allies for potato bug control are Diatomaceous earth and Spinosad… and I find myself using them both throughout the season, depending on the situation that day. The Diatomaceous earth is fast, easy, and great if I only have a small amount of time, or am only available in the daytime. Spinosad is better for bigger infestations or larger larva, or if its a big job- like a lot of plants that have a lot of bugs. I’d recommend trying both and seeing what works for you!
Does Mulching Plants Prevent Potato Beetles?
In my opinion it does not. Multiple articles I read said to mulch all around your plants with a heavy layer of straw, so when the potato beetles crawl out of the ground they won’t be able to find the plants as easily, having a difficult time climbing through the straw. I’m calling BS on this one. If a potato bug can claw its way up and emerge through the dirt, and then walk a mile to find your plants, surely it can climb another couple inches through straw.
And while I do believe that mulching creates an environment that potato bug enemies might like and will help control them in this way, that’s leaving too much to chance for me.
Does Crop Rotation Prevent Potato Beetles?
It doesn’t hurt… and crop rotation is always a good idea for other reasons as well.
When potato bugs emerge in the spring, they travel on foot looking for potato plants and other members of the nightshade family. Reportedly, they can travel miles!
And here’s an anecdote for you. Remember I said that last year they decimated my potatoes, and I didn’t do anything to stop them, and presumably hundreds of them should have been overwintering in my garden? I planted six potato plants right next to this previous potato devastation area, and they are tall and beautiful and have not had one single potato bug on them! We have a second garden about 100 yards from this potato devastation area, where our main crop of potatoes is, which is where I’ve been treating for potato bugs this year. So… who knows.
Should I Dig a Trench? Should I Use Row Covers?
I almost took the plunge and got row covers in preparation for the potato bugs, and I’m so glad I didn’t. The techniques I outlined above, especially with using the Diatomaceous Earth have been very effective at keeping the potato bugs under control. Row covers can be expensive, you have to make sure you stake them down good, and I’ve heard stories that they don’t work all that well for this particular insect.
There is a technique where you dig trenches around your potato garden like a moat and line them with plastic. Supposedly when the potato bugs emerge from the ground and make their way towards the plants they fall into this trench and can’t crawl out. This sounds like a LOT of work, and also like leaving a lot to chance. And what if they emerge already in your potato garden? Then you did a lot of digging for nothing. And if it rains and they fill with water you’ll probably drown a lot of other bugs too, likely a lot of earth worms.
There are a few other similar potato bug control techniques floating around the internet, and in my opinion they are just too much work and not enough reward for the home gardener.
I’d love to hear what methods of potato beetle control have worked for you and also what area of the country you are in. Happy gardening!
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Q: Last summer I spent plenty of time picking potato beetles — a couple dozen every day — from my garden. They start out small and bright reddish orange, then become large and brown, with black stripes. After some research, I found out that they were Colorado potato beetles. I’ve lived here for 70 years and never seen these pests. How can I get rid of them? I don’t want to spend another summer picking bugs — if you miss even one day of picking another plant is gone. Are they only airborne? Can I cover the plant with a net, or what kind of spray treatment can I use? There’s no way I can grow potatoes without getting rid of these bugs.
A: Adult Colorado potato beetles are oval in shape and approximately three-eights of an inch long. The area behind their head is yellow-orange and their wing covers are yellow-white in colour. There are 10 black stripes on the wing covers. Females lay clusters of bright yellow-orange eggs on the underside of leaves. The young larvae are brick red with black heads. As the larvae mature the colour changes to pink, with black heads.
The beetles overwinter in the soil, becoming active in the spring — usually around the end of May. This is convenient timing for the pests, as that is usually the time that newly planted potatoes begin to emerge. The adults feed for a short time, mate, and then lay their eggs. The eggs hatch within two weeks.
Cultural control includes crop rotation. By changing the location of the potatoes you make it harder for the emerging adults to find the plants. This may not be completely effective, but it certainly does help. Laying down a straw mulch can also help. The straw helps confuse the adults when they emerge, and they can actually keep wandering around in the straw — eventually starving to death. Picking them off is a technique that does work (as you know) but can be time-intensive if you have a lot of the little so-and-sos in your garden.
According to the University of Minnesota, diatomaceous earth can work on this insect problem as well. Spreading the diatomaceous earth around the plants and on the underside of the leaves has proven effective. You can also try to find Bacillus thuringiensis var tenebrionis — a bacteria insecticide that doesn’t harm beneficial insects, mammals or humans — and spray it on the plants. It’s most effective on the small potato beetles that measure less than a quarter-inch long.
I would use a combination of the cultural controls, such as straw and crop rotation, along with the diatomaceous earth, and then monitor the plants and pick off any survivors.
Q: I’ve noticed a white crust that is forming on the edges of my indoor plant pots. What is causing this, and will it harm my plants?
A: Water contains salts in varying proportions, depending on the area. These salts, in time, will accumulate and show up as a white or tan-coloured crust or mineral deposit on the edges of pots, or on the inside of the pots at the soil level. The crust may even form on the soil itself or on the plant stems. If you mist houseplants with water high in salts a white residue can form on leaves, and this can lead to permanent leaf spotting.
You can control the problem directly by avoiding tap water. Using rainwater or melted snow to water plants is an economical and effective method of preventing salt buildup. You can also purchase various systems for removing salts from your water supply. These include reverse osmosis, deionizing, and distilling systems. You can also purchase distilled or purified water from many stores.
If you want to get rid of the existing mineral deposits, remove the plant and soak the pot in a solution of equal parts water and white vinegar. After they have soaked, scrub them with a toothbrush or kitchen scrubber. Rinse the pot well before replanting.
Gerald Filipski is a member of the Garden Writers Association of America. E-mail your questions to [email protected] He is the author of Just Ask Jerry. To read previous columns, go to edmontonjournal.com/filipski
- 7 Companion Plants To Battle Those Dreaded Potato Bugs
- Getting Rid Of Potato Beetles: How To Kill Colorado Potato Beetle
- Potato Beetle Signs
- Getting Rid of Potato Beetles
- How to Prevent Potato Beetles
Colorado Potato Beetle Management
- Resistance Management
- Defensive Plant Neighbors
- Leptinotarsa decemlineata
- Understanding Potato Beetles and How to Eradicate Them from the Garden
- Identification, Biology, and Distribution
- Life Cycle
- Organic Control Methods
- Chemical Pesticide Control
- What Is a Potato Bug?
- How To Recognize Potato Beetle Damage
- Crop Diversity Is Key
- The Lifecycle Of The Colorado Potato Beetle
- How To Keep Your Potato Plants, Eggplants, Peppers & Tomatoes Relatively Free Of Potato Beetles
- Attract Helper Beneficials
- How To Get Rid Of Colorado Potato Beetle
- Potato Beetles Are Garden Enemy #1
- Colorado potato beetle control in the home garden
7 Companion Plants To Battle Those Dreaded Potato Bugs
These bugs (Colorado Potato Beetle) are a well known pest that target potatoes, tomatoes, eggplants and even your prized petunias! They not only thrive on the leaves, but are also known to feast on the fruit. If left unchecked, they will affect your garden’s yield and can kill young, tender plants.
There Are Natural Ways You Can Try To Repel These Little Guys
You can get a step ahead of them by growing certain plants that repel them (in ideal locations). I’ve listed a few recommendations below along with a section of tips for getting rid of them (including recipes for a spray which can be used to help keep these pesky fellows at bay).
There are other insects also commonly referred to as potato bugs, I added those at the bottom with reference links for more information on them.
How To Spot An Infestation: If you find leaves have holes or are damaged, check underneath and look for larvae or eggs, they can be a yellow cluster of eggs or larvae with orange and black. If you spot them simply remove the infested part and destroy.
A good resource for pictures of the eggs, larvae and adult beetle along with more detailed information about this pest can be found here: University of Tennessee (pdf).
Natural Deterrents: These are recommended as being suitable for repelling them, intercrop between potatoes or in the space between rows.
- Bush Beans
- Catnip: Grow these in pots because it can be invasive…downside is that once the neighborhood cats figure out you’ve got the good stuff growing, you’ll be herding cats (use in more remote areas rather than city or towns).
- Tansy: Also repels squash bugs.
Getting Rid of Them:
- Manual control: Spot check leaves and shake off any that you see (or hand pick them off but make sure to wear gloves), dispose of immediately by crushing them.
- Did you know: Ladybugs consider the larvae a tasty treat, consider growing items in the garden that will attract them so you have a thriving ladybug population (some ideas: Marigolds, Tansy, Fennel and Dill).
- Diatomaceous Earth: This is a non-toxic method of pest control, simply dust the leaves and surrounding soil with the powder and repeat after each rainfall.
Keep In Mind: The larvae will go underground to pupate and then emerge as adults after 10 days or so, you’ll likely need to continue removal methods until all the adults and larvae have been dealt with.
Homemade Repellent Teas or Infusions: Here are two different recipes you can try, once they’ve cooled pour into spray bottles and apply as needed (for best results spray fresh applications after each rain).
- Tansy or Marigold Infusion: Fill a pot with freshly picked tansy (or marigolds), cover with water and bring to a boil. Reduce to simmer and cook until liquid has been halved. Strain, cool and use as needed.
- Wild Mustard Tea: Steep 4 whole cloves, a handful of wild mustard leaves, a clove of garlic in 1 cup of boiling water for 10 minutes. Remove from heat and cool, then use as spray. Source: Jerry Baker’s Bug Off!: 2,193 Super Secrets for Battling Bad Bugs, Outfoxing Crafty Critters, Evicting Voracious Varmints and Much More!
Here are a couple other insects that are commonly mistaken as potato bugs (with resources to check out):
- Pill Bugs (pillbugs), Roly Polys or Rolly Polly Bugs (because they roll up into a ball when aggravated). These guys are more attracted to dead plant matter (though they will munch away on young ones too). You can try attracting them away from the garden by setting out corn cobs and then dispose of them once they gather on the cob. You can find more information about them here.
- Jerusalem Crickets: These are ugly! They feed on dead plant matter, you can learn more about them here.
Getting Rid Of Potato Beetles: How To Kill Colorado Potato Beetle
Potato beetles are pests of plants in the nightshade family. Potatoes are one plant they devour, but the beetles also eat tomatoes, eggplants and peppers. Both the adults and the larvae eat the leaves of these plants. Getting rid of potato beetles is a priority for the vegetable gardener due to the range of plants the pest can infest. It’s important to know how to look for potato beetle signs so you can be ready to eradicate the insects.
Potato Beetle Signs
Both adult beetles and the larvae feed on the leaves of nightshade plants. The adult beetles are small yellow and black striped beetles. The young are hard bodied red insects with a row of ridges across their humped backs. The young also have a line of black dots along each side of their bodies.
The eggs of potato beetles are bright orange and
laid on the underside of leaves. Foliage damage starts out as small holes and becomes larger ragged patches. The damage to the leaves can reduce the vigor of the plant and reduce yield. Controlling Colorado potato beetle will increase your crops and help prevent egg laying and the return of the insect the next season.
Getting Rid of Potato Beetles
Controlling Colorado potato beetle begins with an assessment of the damage. In most cases, the foliar damage isn’t enough to kill a plant but if infestation occurs early in the growing season you should kill Colorado potato beetle. Insecticides should only be used when damage is severe and there is more than one insect per plant. Hand picking can remove many of the pests. A natural bacteria, Bacillus thuringiensis, is useful as a non-toxic control.
Several sprays exist to kill Colorado potato beetle. Timing is an important consideration, in order to get the maximum number of insects. Small larvae are easier to control than adults and mature larvae, therefore, spray when the larvae have just hatched in spring. Use a chemical with pyrethroid or spinosad, which offer control on each species of nightshade.
How to Prevent Potato Beetles
Adult beetles overwinter in the soil and then crawl out to begin feeding and laying eggs. Check the backsides of leaves for the orange eggs and crush them to prevent a future generation of the pests.
Another way how to prevent potato beetles is to keep beds free of debris that gives the adults hiding places. Remove old plants each season and till the vegetable bed. Do not plant nightshade plants in the same location each year but rotate to prevent putting them where the insects already live.
Colorado Potato Beetle Management
University of Kentucky College of Agriculture
The common black and yellow-striped “potato bug”, a very familiar insect to home gardeners, is the most serious insect pest of potatoes. Both the striped beetle and the black-spotted, red larva feed on potato leaves. Their damage can greatly reduce yield and even kill plants. In addition to potato, Colorado potato beetle can be a serious pest of tomato, eggplant, and pepper.
Figure 1. Colorado potato is commonly referred to as the ‘potato bug’.
The Colorado potato beetle is notorious for its ability to rapidly develop resistance to insecticides that are used repeatedly for control. This has been a serious problem on the east coast for some time, and is becoming more of a problem in Kentucky. With a limited number of insecticides available, some homeowners feel they have exhausted their control options when it becomes resistant to one or more insecticides.
Colorado potato beetles overwinter in the soil as adults. They become active in the spring as temperatures rise and begin to feed on weeds and volunteer or early planted potatoes, even entering the soil to attack emerging foliage. Female beetles lay orange-yellow eggs in batches of about two dozen or so on the underside of the leaves. Each female can lay 500 or more eggs over a four to five week period. Eggs hatch in four to nine days and the larvae begin to feed on potato foliage.
The larvae are humpbacked with two rows of black spots on each side. They usually feed in groups and damage can be severe. The larval stage lasts two to three weeks.
Figure 2. Colorado potato beetle larvae are humpbacked with two rows of black spots on each side of the body.
Full-grown larvae burrow in the ground to pupate. In five to 10 days, the adult beetle emerges. This insect can go from egg to adult in as little as 21 days. The newly emerged adult female feeds for a few days before egg laying begins. There are two full and occasionally a partial third generation each year. If foliar sprays are used, an effort should be made to treat just after most eggs have hatched but before serious plant damage occurs.
Insecticides in the same chemical class usually have the same mode of action, the same method of killing the insect. Resistance develops more rapidly to an insecticide when that insecticide is used repeatedly as the only control measure. Repeated use of one class kills susceptible beetles, leaving those that are resistant. Overuse of one insecticide may favor the development of resistance to other insecticides in the same chemical class. Consequently, to delay or prevent resistance it is important to avoid repeated usage of one particular insecticide by rotating the insecticides used.
Rotation needs to be among different classes of insecticides. This is done by switching IRAC modes of action groups with each application. For example, rotation between two pyrethroids in IRAC group 3A would not be as effective as a group 3A followed by a group 4A in rotation. Because both group 3A’s are in the same class of chemicals and have the same mode of action, nothing is gained with this type of rotation.
Figure 3. IRAC mode of action group listing is on the front of most commercial insecticide labels.
Bacillius thuringiensis var tenebrionis (Bt) is effective against small larvae (less than 1/4 inch) and should be applied at egg hatch or when larvae are first seen. A premature treatment may lose much of its effectiveness before the eggs hatch. Larger larvae are more difficult to control with Bt. Azatin, an extract of the neem seed, prevents the larvae from developing normally.
Frequently, control failures with Colorado potato beetle are due to other factors besides just insecticide resistance alone. Timing of sprays is critical for control. Overwintering beetles are attracted to fields over a period of several weeks; spraying an insecticide too early may only control a portion of those beetles. However, waiting until larvae are nearly full grown also increases the chances of control failure. Small larvae are much easier to control with an insecticide than large ones. Using the correct amount of insecticide as well as obtaining complete coverage of the plants is important.
Insecticides should only be used when needed. Potato plants can withstand considerable defoliation without yield loss. Plants can loss up to 30% of their foliage without yield loss. Generally, insecticides do not need to be applied unless there is more than an average of one beetle or larva per plant. Additionally, some beneficial insects such as birds, predatory stink bugs, and parasitic flies will help to reduce Colorado potato beetle numbers somewhat.
Other non-chemical control measures such as hand picking of adult beetles and immature stages is encouraged as this will aid to delay the development of resistance. Hand picking can be particularly effective in reducing the numbers of overwintering beetles coming to the young plants in the spring. Resistance by Colorado potato beetles should be managed on a field to field basis. While they may be resistant to one insecticide in a particular location, those in other areas within the same county may not have developed resistance to that insecticide.
CAUTION! Pesticide recommendations in this publication are registered for use in Kentucky, USA ONLY! The use of some products may not be legal in your state or country. Please check with your local county agent or regulatory official before using any pesticide mentioned in this publication.
Of course, ALWAYS READ AND FOLLOW LABEL DIRECTIONS FOR SAFE USE OF ANY PESTICIDE!
Photos courtesy Ric Bessin, University of Kentucky Entomology
Colorado potato bugs, also know as Colorado potato beetles, were first observed feeding on potatoes in Colorado in 1859, and quickly spread across the U.S. They are now found in every state and are a major pest for both home gardeners and commercial agriculture. Most pesticides available to the home gardener are ineffective against potato bugs, so careful monitoring and organic gardening strategies are critical to controlling them.
CC flickr photo by annethelibrarian
Potato Bug Identification
Adult potato bugs are 3/8 inch long with an orange head and a yellow body with black stripes. They overwinter in the soil and emerge in late spring, around the same time potato vegetation appears. They lay clusters of small, orange eggs on the undersides of leaves. Young larvae are deep red with black heads; older larvae are pink to salmon with black heads. All larvae have black spots on the sides of their bodies. In warm weather, larvae may mature in as little as 10 days. In regions with long, hot summers, potato bugs may have two or more generations each year.
Damage from Potato Bugs
Potato bugs feed on the leaves and stems of potato plants, and in large numbers, can completely defoliate the plant. Potato plants can usually withstand infestations early in the season, but damage is severe if it occurs when the potato tubers are actively growing, usually right after blooming.
Potato bugs also feed on any plant related to potatoes, including peppers, tomatoes and eggplants.
Potato Bug Prevention
Tilling the soil in late fall or early spring can kill overwintering potato bugs, reducing their numbers. Crop rotation is largely ineffective because potato bugs can fly for many miles. Try growing potatoes every other year to reduce potato bug populations. Remove all plant debris in the fall, and choose early-maturing potatoes that are ready for harvest in 80 days or less. These varieties will mature before adult potato bugs are actively feeding. Plant potatoes as soon as the soil can be worked in the spring.
Control of Potato Bugs
Handpick potato bugs, as well as their larvae and eggs, and drop them in a bucket of soapy water to destroy them. In larger gardens, where handpicking is not practical, spray the potato plants with Bacillus thuringiensis. This naturally occurring soil bacterium paralyzes the gut of potato bugs, slowly starving them. Read package labeling, though, and buy Bt labeled specifically for use on potato bugs, since many products work only on moth larvae.
For Further Reading
University of Kentucky – Colorado Potato Beetle Management
University of Minnesota – Colorado Potato Beetles in Home Gardens
Under these conditions, the Bt-combat method works well:
- potato bugs and larvae need to feed on the bacterium
- at the time of the treatment, temperatures need to be 15 degrees Celsius or higher
- the treatment needs to be applied in the early hours of the morning because at that time the insects will take in the most food
- the spray or the spray solution needs to be sprayed directly onto the insects
- supplementary, all tops and bottoms of the infested plant will be treated
The active agent causes an immediate feeding stop. In the further course, bugs and larvae die. Approved products for the use in small gardens such as Novodor FC from Biofa are already applied to the brood in the larvae stage one and should therefore be administered at an early stage.
The tropical Neem tree provides ingredients that help against potato bugs and other biting or sucking harmful insects. With products, such as NeemAzal T / S, you can fight the pests in your home garden in a healthy and environmentally-friendly manner. The remedy is made from the seeds of the tree in form of an extract containing a high proportion of azadirachine. This active substance is not directly fatal. Rather, the life cycle’s first stage is inhibited by a feeding stop, followed by the decreased ability to propagate. This is how the development proceeds.
- best timing for the treatment is the fifth day after egg deposition
- only produce the needed amount of spray solution on the day of treatment
- Neem inhibits the hatching of the eggs so that no development occurs after the first larvae stadium
You can improve the success of Neem-containing products by using the bacterium Bacillus thuringiensis two or three days afterwards because these two biological treatments work well together.
Pyrethrin and Rapeseed Oil
Under high pressure of pest infestation, plagued amateur gardeners decide to use a combination compound of pyrethrin and rapeseed oil, such as “Spruzid Neu”. The pyrethrum contained in it was regarded as a hope in the battle against the disastrous potato bugs. However, the pests developed a resistance, so the efficacy decreased to less than 20 percent. Thanks to intensive research, the effectiveness was optimized by adding natural rapeseed oil.
Although the control agent is not entirely harmless to the environment and to your health, it is currently still approved for use in small gardens. In Germany the “Bundesamt für Verbraucherschutz und Lebensmittelsicherheit (BVL)” is responsible for a database containing all the permitted substances for combating the pest infestation, including the date of the approval ending.
Approved for organic farming in the European Union is the active substance spinosad, which has also proven effective against potato bugs. If all purely natural control strategies are not working out, this alternative is available to get rid of the potato pest. It is obtained from special bacterial strains and amino sugars.
The use of the insecticide may only be carried out with special protective precautions such as the wearing of protective clothing and gloves. In addition, it is dangerous for bees and other beneficial organisms, so it must not be applied to flowering plants.
Online Information Service
Because the effectiveness of ecological control measures depends on the fact that they are applied at the right time, the “Landesanstalt für Landwirtschaft” provides an information service that you can also use as a hobby gardener. For each region, a prediction system based on local incidents is available.
Considering weather data and the development process from egg to larvae, the optimal time at which you should use the selected compound is calculated. Since the forecast calculation works with a lead time of one week, you have sufficient time to choose the control method and obtain the appropriate means. This service is available free of charge online and can be used in full by both commercial farmers and private gardeners.
In the ecologically managed garden, you can prevent an attack by potato bugs through the means of purely natural remedies or stop them right away in the beginning. In the following, we will present you with even more practical methods. To avoid that these clever pests adjust to a method and develop a resistance, please always change the active ingredients.
Horseradish liquid manure
In spring, bring out repeatedly a horseradish (Armoracia rusticana) manure in your patches with potatoes and other nightshade family plants. This plant manure keeps the potato bugs which are crawling out the ground from laying their eggs on the leaves. In addition, horseradish manure serves as a natural control agent in the first larval stage.
To produce the liquid manure, follow these guidelines:
- layer one kilogram of fresh or 300 grams of dried horseradish in a wooden barrel
- pour over ten liters of collected, filtered rain water or stale tap water
- put outside on a sunny, warm place in your garden located offside
- cover the container with wire mesh and not wish a lid
- stir the liquid multiple times a day for oxygen to enter
Already after two to three days the solution has a certain degree of effectiveness against the potato bugs. However, the liquid only reaches its full potential after two weeks, when the liquid is completely fermented. Strain the plant parts and fill the horseradish liquid in a watering can or a pressure sprayer. Preventively spray the plants weekly. If the potato bugs or their larvae are already on the foliage, get rid of the pests by applying this natural product every three days.
As a natural soil aid, rock flour has made a good name for itself within the sphere of ecological agriculture. The fine material also makes a valuable contribution in the defense of potato bugs and other pests that want to eradicate the foliage of your crops. If you powder the dewy potato plants regularly in the early morning hours on the top and bottom of the leaves with rock flour, the voracious plague will soon lose its appetite.
This is true for adult bugs as well as larvae. As a single control agent, rock flour is not suitable, but as a component in the strategy it is nevertheless of value. At the same time, the natural product strengthens the resistance of your plants in an environmentally friendly manner.
Among the house remedies for potato bugs, coffee grounds are the best for the private garden. If the young plants reach a growth height of 10 cm, spread the dried coffee grounds every 4 weeks on the still moist leaves in the morning. The coffee powder should not be used at shorter intervals because it decreases the pH-levels.
The ingredients found in a Thuja have the potential to permanently offend potato bugs and their brood. After a cutting of the conifers, keep enough material to make a tea. To do this, pour the water over the cut parts and let it soak for 24 hours. The next day, you sift out the plant material, fill the liquid into a hand sprayer and treat the potato plants. Especially for the prevention as well as at the early infestation stage, this procedure perfectly complements other ecological methods.
Potato bugs are not big admirers of peppermint. This fact was discovered by wise eco-gardeners. So, repeated spraying with mint broth makes a valuable contribution to the defense of these pests. In contrast to liquid manure, the broth is produced within a short time. To do this, mix the fresh plant parts with water and allow it to simmer for 30 minutes. After the broth is cooled, it can be immediately sprayed on the potato plants.
Defensive Plant Neighbors
One of the many advantages of a mixed culture is that compatible plant neighbors protect each other against diseases and pests. Commune your potato plants with the following ornamental and cultivating plants and attacking potato bugs are repelled or irritated in such a way that they are looking for another area for their nursery school.
- pepper mint
At the same time, mulch regularly with fern and the pests will not enjoy living in your potato patch anymore.
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Colorado potato beetles pose such a grave threat to potato crops that flamethrowers have been used to control them. However, you do not have to go to such extremes in your garden.
We at Gardener’s Path provide a number of natural control methods to use against this voracious pest – and if necessary, tips on how to use insecticides as well.
Although not discovered until 1811, Colorado potato beetles quickly spread from the Rocky Mountains to the East Coast by 1874, and reached Europe a few years later.
Left unchecked, these beetles can devour an entire crop of potatoes. And they also lay waste to these fruits and vegetables:
- Ground Cherry
Infestations are so serious that they have even been considered part of international warfare!
In the 1950s, East Germans called these pests “Yankee beetles” and accused the United States government of dropping them from planes during the Cold War. (There was no evidence to support this claim.)
Understanding Potato Beetles and How to Eradicate Them from the Garden
- Identification, Biology, and Distribution
- Life Cycle
- Organic Control Methods
- Mechanical and Physical Controls
- Floating Row Covers
- Trap Crops
- Predators and Disease
- Organic Insecticides
- Cultural Controls
- Crop Rotation
- Mechanical and Physical Controls
- Chemical Pesticide Control
Identification, Biology, and Distribution
Colorado potato beetles, aka potato bugs, are about 1/4 to 1/2 inch long. The area behind their heads is orange-yellow. You can easily identify them by the 10 alternating yellow and black stripes on their shells.
These voracious insects can be confused with false potato beetles (Leptinotarsa juncta), which are not pests. You can tell the difference because the false potato beetles have alternating white and black stripes on their shells.
Potato beetle larvae hatch from yellow-orange eggshell clusters on the bottom of leaves. Newly hatched larvae are bright red. The older orange-pink larvae are about 1/2 inch long.
Larvae of all stages have black heads, and can be identified by the two rows of dark spots on each side of their humps.
These insects can be found in every state except California, Nevada, Hawaii, and Alaska. They are also pests in every Canadian province, and in Central America. The beetles have spread to more than 6 million square miles across Europe and Asia.
Depending on the climate, these pests can live through the winter as adults in gardens, field margins, and windbreaks. In less favorable climates, the adults may overwinter in your soil.
The adults lay yellow to orange eggs about 1 millimeter long on the bottom of leaves, where they hatch into larvae.
The larvae go through four growth stages (instars), and the fourth instar larvae cause the most damage to food crops. These hungry larvae are responsible for up to 75% of the damage to a crop.
When the larvae complete this phase of their life cycle, they drop to the ground and burrow several inches down before pupating.
Adult beetles emerge 5-10 days later, and start feeding and mating on their host plants. If conditions are not favorable, the adults may not emerge until spring.
A single female can lay over 500 eggs over a 4 to 5-week period, and they can mature from larvae to adult beetles in 1.5-3 weeks, depending on the climate.
Organic Control Methods
Once you have identified these insect pests in your garden, don’t panic! Potato plants can lose up to 30% of their leaves and stems without any loss of yield.
Their most critical time is after flowering, when the tubers have begun to bulk up. However, you will want to take action before these fiendish pests take over.
Your immediate reaction may be to reach for an insecticide. This may not be the best strategy, since Colorado potato beetles are frequently resistant to pesticides.
Instead, your best bet is to consider a combination of different types of organic control methods.
If you are a home gardener, one of the first and most effective things you can do is to go on the offensive and pluck the slow-moving beetles off your plants. This is easiest to accomplish on a sunny, warm day when the pests are out and about.
Just drop them into a container of soapy water! That will dispense of these nasty pests quickly and easily.
While it may be the most satisfying to kill the adults, make a point to get as many of the larvae as you can, as they cause the most damage. And don’t forget to crush any egg masses that you find on the bottom of the leaves, which often appear around the same time that shoots are first emerging from the soil.
Be sure to wear gloves, and wash your hands afterwards. The bugs contain a chemical that may irritate your skin.
Floating Row Covers
Floating row covers can help protect your plants from insect infestations. Use a specially designed lightweight floating row cover and thoroughly secure the material to the ground with soil or staples.
Ensure that you are not covering plants in an area where you grew them before. Since these pests can overwinter in the soil, you could get an accidental infestation under the floating row cover if you are not careful.
Another way to protect your plants from L. decemlineata is to grow plants that attract these insects. If you grow trap crops around the perimeter of your garden, the beetles will colonize the first host they see.
This can delay their spread into your garden and give you a chance to go on the offensive.
Potatoes are the most common trap crops used for L. decemlineata. However, any host plant that they enjoy munching on will work as a trap crop, including other members of the Solanaceae family such as ground cherry, horse nettle, tomato, and buffalo-bur.
Commercial tomato growers have had great success using potato plants as trap crops. A Canadian test found that tomato yields increased by 61-87% using this approach.
You can also grow non-host crops like corn in the area. This can confuse the beetles and delay infestation.
Predators and Disease
Fittingly, you can use other types of insects (or even spiders) to control L. decemlineata. Some well known beneficial insects for this purpose include ladybugs (aka lady bird beetles) and green lacewings.
Live ladybugs in various quantities available from ARBICO Organics
Normally thought of as a menace in their own right, several types of stinkbugs prey on L. decemlineata. These include spined soldier and two-spotted stink bugs.
Green Lacewing eggs, larvae, and adults are available from ARBICO Organics
Parasitic wasps are highly specialized for their hosts, and Edovum puttleri can help control your infestation. This wasp will lay its eggs in those of the beetles. Myiopharus doryphorae, a type of tachinid fly, parisitizes these pests as well.
You even have the option to use microbial insecticides against L. decemlineata. One type of bioinsecticide contains Bacillus thuringiensis var. tenebrionis (Bt-t) bacteria.
This strain produces a toxin that targets the young larvae, so it should be applied every few days as soon as the eggs start to hatch. If you apply it too early, the bacteria won’t survive until the larvae emerge, so the treatment won’t work.
Bt-t is sensitive to UV rays, so you should spray late in the evening or on cloudy days. Also make sure that it won’t rain within 8 hours after you have sprayed. You can tell if the treatment is working because the larvae will turn black.
However, like other organisms, insects can evolve resistance to their attackers, and some Colorado potato beetles display resistance to Bt-t.
Another microbe that can be used to attack these garden pests is the fungus Beauveria bassiana, which can be used against both adults and larvae.
BotaniGard® ES Beauveria bassiana spores via ARBICO Organics
Combining this fungus with Bt-t can enhance the effectiveness of this type of control.
Several organic insecticides can help to control L. decemlineata. However, often when you spray an insecticide, you also kill the natural enemies of the pest you are trying to control.
One organic insecticide that is particularly effective at killing these pests without slaughtering their natural enemies is spinosad. This compound acts best against young larval beetles, so you should apply it when you see the eggs hatching.
Monterey Garden Insect Spray Concentrate (spinosad) via ARBICO Organics
You should spray neem oil in the evening, so it won’t affect beneficial insects. You will need to reapply the neem oil frequently. It also acts most effectively against the young larvae.
BONIDE® Neem Oil Concentrate via ARBICO Organics
Pyrethrins are another option to target the young larvae. But keep in mind that these compounds have a short half-life – only 12-13 hours.
PyGanic Gardening Pyrethrin in various sizes via ARBICO Organics
One of the primary pyrethrin components almost completely degrades after 5 days on tomato or potato leaves, and some L. decemlineata populations have developed resistance against this class of insecticides.
If you have had problems with L. decemlineata in the past, crop rotation can be the most important cultural control for this pest. This method delays infestation and reduces the early season populations of beetles.
A Journal of Economic Entomology study of commercial potato fields on Long Island, New York, found that rotation with non-host plants like rye or wheat decreased the density of early season adult beetles by nearly 96%. This effect wore off later in the season.
One thing you can do to enhance the success of crop rotation is to mulch with straw early in the season. This will make it even more difficult for the beetles to find your crop.
Plus, it has an added bonus: this environment favors predators of the beetles!
Rotating your potato or tomato crops every few years is a good strategy to reduce disease and beetle outbreaks. Many diseases are soilborne, and the beetles frequently overwinter in the soil.
Implementing a no-till system of cover crops has been reported to help farmers greatly reduce their pesticide use against L. decemlineata.
There are several reasons why no-till works so well. One is that they can harbor the beneficial insects that serve as predators to the beetles. Another is that they discourage the pests from colonizing your plants.
You should consider planting multiple types of cover crops like buckwheat and Sudan grass to attract different types of beneficial insects.
Another strategy is to plant your cover crops sequentially, so they will flower at different times. This will help to increase the diversity of beneficial insects available to attack the potato beetles.
While you do want to attract the beetles if you are planting trap crops, this is not the case when you are growing cover crops close to your potatoes or tomatoes.
With no-till practices, you should purge any alternate hosts like nightshades, ground cherry, jimsonweed, horse nettle, or henbane that are growing in the area. This will prevent the beetles from feeding on these host plants and infecting your crop after they come out of the ground in the spring.
Chemical Pesticide Control
Modern potato growers frequently use chemical pesticides to control this pernicious pest. If the infestation in your home garden is severe, you may want to consider this option.
A. Alyohkin and co-authors claimed “the Colorado potato beetle played a large role in creating the modern pesticide industry” in a 2008 issue of the American Journal of Potato Research.
Your first thought might be to reach for a classic insecticide like Sevin (carbaryl). However, you should hold off until you have consulted with your local county extension agent.
Colorado potato beetles typically exhibit strong resistance to such a pesticide due to its wide usage in the past. The population as a whole is resistant to at least 56 different insecticides.
However, no one beetle is resistant to all insecticides. Agricultural experts can tell you which ones are likely to work in your area. Esfenvalerate may be one to try.
Your best bet for chemical control is to spray after most of the eggs have hatched but before your plants are seriously damaged. Take care that you apply these pesticides in a safe manner and follow all the instructions on the label.
You should rotate your insecticide use among different classes, so the pests will not develop resistance.
Keep in mind: it is likely that the natural methods described to control these pests in your garden will be effective, without the need for pesticides.
Go Forth and Garden
If you are faced with an onslaught of these unwanted visitors to the garden, you can start by handpicking the mature pests and their larvae, and crushing their egg masses.
Natural control methods range from waging war with predatory insects and microbial insecticides to cultural methods like using trap crops and implementing a no-till strategy. If necessary, you can rely on the judicious use of insecticides.
Gardener’s Path provides a range of options for you to save your crop!
Have you waged war against Colorado potato beetles? If so, let us know how it went in the comments. We would leave to hear what worked or didn’t work for you. And read on for more articles about insect pests here:
- Managing the Aphid
- Doing Battle with Japanese Beetles
- How to Rid Your Garden of Cockroaches
© Ask the Experts, LLC. ALL RIGHTS RESERVED. See our TOS for more details. Uncredited photos: .
About Helga George, PhD
One of Helga George’s greatest childhood joys was reading about rare and greenhouse plants that would not grow in Delaware. Now that she lives near Santa Barbara, California, she is delighted that many of these grow right outside! Fascinated by the knowledge that plants make chemicals to defend themselves, Helga embarked on further academic study and obtained two degrees, studying plant diseases as a plant pathology major. She holds a BS in agriculture from Cornell University, and an MS from the University of Massachusetts Amherst. Helga then returned to Cornell to obtain a PhD, studying one of the model systems of plant defense. She transitioned to full-time writing in 2009.
If you’re trying to grow potatoes (or any member of the hemlock family or solanaceous crops) one of the most often encountered problems is the Colorado potato bug or beetle.
Larva and adults beetles prey upon potato plants by eating both the blossoms and the leaves.
In addition to potato plants, these voracious little beetles also lay waste to other members of the hemlock family, such as peppers, eggplant and not to mention creates tomato plant problems.
When plants loses a great number of leaves, its vigor and ability to produce fruit are hampered. All of these plants will suffer reduced production levels if potato beetles continue to consume your plants.
What Is a Potato Bug?
Colorado potato beetles (leptinotarsa decemlineata) are most commonly found in the southwestern areas of the United States. You will begin to see the adults emerge late in the spring time when you’re potatoes are just beginning to establish themselves and grow well.
Adult potato beetles, potato bugs or Jerusalem crickets are easy to spot because they are quite dramatically marked. Their wings are black and striped with a yellow-orange color, and their heads are orange with black spots.
You’ll find the adults amongst the foliage of your potato plants. Unless you intervene you will soon see clusters of reddish potato beetle larvae on the tips of your potato plant branches.
If you are growing eggplant, the potato bug larvae will be gray. As they get larger, you will notice the potato beetle larvae beginning to sport black dots on their sides.
How To Recognize Potato Beetle Damage
During the potato beetle larval stage these bugs are hungry little critters but where do potato bugs live?
They first go for the tastiest and most tender parts of plants. You can find them infesting gardens with solanaceous plants or those that are from nightshade family.
For this reason, they will usually eat the flower buds from potato plants before eating the leaves.
They move very quickly, and if interfered with they will strip all foliage from your potato plants.
It is important to note that this is more likely to happen when you plant a mono crop.
In other words, if you have all potatoes, tomatoes or other hemlock type plants you are more likely to lose your whole crop.
Crop Diversity Is Key
If you have a mixed crop, colorado bugs may ignore some plants and focus on others, so it’s a good idea to keep a diversified organic garden.
This type of garden is more likely to attract beneficial insects which are natural predators of potato beetles.
When you have a good assortment of beneficial fauna in your garden, you can be sure that potato beetle eggs, larvae and even adult beetles will be consumed.
You want to have a good mix of ladybugs, ground beetles and small wasps. In this way you can be certain that eggs, larvae and beetles will have to fight to survive.
The Lifecycle Of The Colorado Potato Beetle
Adult potato beetles can live through the winter by hiding under the bark of trees or other cover to protect them from freezing.
When the weather warms up in the middle of the spring time, they come out of hiding and seek out potato plants or other hemlock type plants.
Once they find the type of plants they need, they eat, mate and lay eggs.
Within a couple of weeks, the eggs hatch and the larvae will begin feeding on the plants. This goes on for another couple of weeks until the larvae become pupa.
From the laying of eggs to the time the pupa become adults can take 30-45 days.
The amount of time is dependent upon the weather. In cooler weather, this transformation takes longer. In warm weather the entire process usually takes about 30 days.
When you live in a warm climate, you may get a double dose of potato beetles every year!
When the cycle of metamorphosis takes only 30 days, it is entirely possible for it to be completed twice in a growing season.
- Blister Bug Beetles
- Flea Beetle Control
- Controlling June Bugs
How To Keep Your Potato Plants, Eggplants, Peppers & Tomatoes Relatively Free Of Potato Beetles
Organic control is most effective for pest management. You might think spraying pesticide would be a good idea, but you’d be wrong.
You will have far more success fighting off potato beetles with an arsenal of natural weapons.
There are a number of organic ways of controlling potato beetles and maybe some other pests such as tomato fruitworm, aphids, and others. Among them include:
- Pick the potato beetles off from the soil or plant as you see them.
- Attract beneficial insects to your garden.
- Line trenches between rows with plastic.
- Mulch the soil and plants heavily with straw.
- Practice crop rotation
These natural solutions are far better than chemical insecticides because as time has passed, the Colorado potato beetle has developed commercial insecticide resistance from a vast majority of brands.
For this reason, it is more effective to use a variety of organic methods to catch potato beetles off-guard.
One example is making use of essential oils such as a neem oil, which is known as an effective solution against garden pests.
Diatomaceous earth also does a great job of eliminating insects and other harmful insect pests in your potato fields.
Attract Helper Beneficials
The best beneficial fauna or natural enemy to help you in your fight against potato beetles include:
- Predatory Stink bugs (hemiptera pentatomidae)
- Double eyed soldier bugs (perillus bioculatus)
- Parasitic Wasps
- Domestic Fowl
- Ground Beetles
- Box Turtles
- Spotted lady beetles (coleomegilla maculata)
You can attract a lot of beneficial insects for biological control by planting flowers amongst your potato crops.
In addition to insects that will help you fight potato beetles, planting flowers will also attract pollinators such as butterflies and bees so it’s a win-win all around.
How To Get Rid Of Colorado Potato Beetle
Along with forming an alliance with beneficial fauna, there are a number of steps that you can take to keep potato beetles at bay. Among them are:
1. Rotate your crops. This is a very effective way to baffle potato beetles and to prevent them from being able to find your crops. It’s a good idea to alternate grains with tubers to prevent having potato beetles establish themselves.
2. Dig trenches between your rows of potato plants. These trenches should be a foot wide and dug at a 45 degree angle. Line each trench with black plastic. When the potato beetles fall into the trench, they will be trapped.
3. When your young potato plants have emerged and are growing well, mulch around them with straw or hay. Be sure to do this early enough that potato beetles have not yet found your plants. When they come looking and make their way across the straw or hay, they are very likely to encounter the one of the natural predators you have cultivated.
4. Use floating row covers to protect your potatoes once you have mulched them. Open them up once a week and examine your plants to be sure that potato beetle larvae or adults are not present. If they are, remove them by hand.
5. Keep chickens, ducks, geese and/or guineas. Once your potato plants are fairly mature (one foot tall) you can let your flock wander through them from time-to-time to pick off potato beetles.
6. Carry a bucket of warm soapy water with you when you examine your potato plants. It’s also a good idea to carry a little mirror with you so that you can easily examine the undersides of your potato leaves.
If you see larvae or adult beetles, remove them and drop them in the soapy water. Doing this every day will greatly reduce the number of potato beetles in your garden. Using an insecticidal soap is a good potato bug killer and will make killing pill bugs, sow bugs and potato bugs easier.
7. Plant potato beetle resistant varieties of potato such as “King Harry”. This type of potato plant has a great many leaf hairs, making them undesirable to potato beetles.
8. Mix buckwheat plants into your garden. Potato beetles don’t like them, but predatory wasps do. The blooms of the buckwheat plants will attract these beneficial garden insects at just the right time to help you battle potato beetles.
9. If you see lots of larvae on your plants, you may want to spray with organic spinosad insecticide. This organic pesticide is produced using fermentation.
It is save for indoor and outdoor plants, fruit trees, flower gardens, lawns and veggie gardens. It is listed as safe for use in organic food production by the USDA National Organic Program.
Another natural potato beetle control option is Bacillus thuringiensis. Learn more about Bacillus thuringiensis (bt) here.
10. Throughout the growing season, continue to add coarse mulch around your potato plants. This can be straw or hay or even grass clippings or leaves. This type of mulch provides habitat for natural potato beetle predators.
Potato Beetles Are Garden Enemy #1
Because they are so adaptable, reproduce so prolifically and wreak havoc with all kinds of hemlock crops, potato beetles are the scourge of many a gardener’s existence.
The challenge of coping with their notorious ways has spurred many a scientist into action.
You can find lots of interesting information at the websites of several major universities. Additionally, there is even a website dedicated entirely to the contemplation of the potato beetle problem.
It is Potatobeetle.org where you will find articles, tips, studies, anecdotal information and even potato beetle haiku and artwork submitted by young organic gardeners in the making.
The main thing you should remember when battling potato beetles is that you will probably never overcome them.
However, if you adopt a Wile E. Coyote sort of approach to them and keep devising one fiendish plan of attack after another, you have a good chance of keeping them at bay and having a bit of fun doing it!
Colorado Potato Beetle, Leptinotarsa decemlineata
The adult Colorado Potato Beetle has an oval body that is about 3/8 inch long. Adults overwinter in the soil and are yellow-orange in color with several black stripes down their back. Eggs are an orange/yellow color and approximately ½ inch in length often found fixed in clusters of 10 to 30 on the underside of the leaves. After hatching, larvae are orange/red in color and feed voraciously on plant foliage as they mature. Over the developmental cycle Colorado Potato Beetle larvae grow larger and closer to dark red in color with black spots on the sides of their body. Larvae drop to the ground and pupate there. Depending on the time of the year, adults will either emerge to mate and lay more eggs or remain in the soil to emerge in the spring.
After overwintering, adult Colorado Potato Beetles surface in spring after rain and when the ground temperature has reached 57°F at their hibernation depth. They then feed on young potato leaves or foliage of other host plants such as Eggplant, Tobacco, Tomato and more. After mating, the female immediately begins to lay eggs. The adults and the larvae can partially or totally destroy the foliage of their host plant.
Colorado Potato Beetle Control:
Control can be difficult but is achievable. Multiple methods may need to be used during a growing season:
- During spring, cover plants with Agribon or Harvest Guard to exclude the mobile beetles.
- During the late summer or early autumn and in spring, apply Beneficial Nematodes to control the larvae.
- For the larval through adult stages, Spinosad, the active ingredient in Monterey Garden Insect Spray works to control the Colorado Potato Beetle.
- Beauveria bassiana, the active ingredient in Botanigard, kills both larvae and adults – use either as a soil drench or as a foliar application to the plants.
- Ladybugs and stink bugs are the most effective natural enemies of the Colorado Potato Beetle. We knew those stink bugs would come in handy for something!
- Several organic insecticides provide some control of this beetle: Pyrethrins, AzaMax, and Neem Oil are included in this list.
Don’t forget to tend to Cultural Practices that help to reduce the habitat for these pests:
- Mulch with locally sourced material making sure to inspect for pest eggs or other life stages.
- Clean up leaves and debris regularly and thoroughly.
- Plant Cover Crops and Pollinating Plants around your growing area to attract Beneficial Insects.
- Hand-pick the adults when you see them. Some gardeners like to keep a butterfly net on hand to help trap them. Once you have them, dunk them in a pail of soapy water.
Colorado potato beetle control in the home garden
One of the familiar pests of the garden is the Colorado potato beetle, also known as the “potatobug.” It’s interesting to note that potatobugs were very familiar to Iowans through the first half of the 20th century but that they seemed to disappear for a while only to re-emerge as a major pest problem in the 1990s and remain widespread and destructive to this day. Colorado potato beetles feed on the foliage of potato, tomato, eggplant, pepper and other related plants. They are most damaging to potatoes where the defoliation reduces yields and may even kill plants.
Colorado potato beetles are approximately 3/8 inch long with an oval, convex body. There are 10 alternating yellow and black stripes on the wing covers. The adults spend the winter hiding in wooded areas and other protected locations and then begin to lay eggs on host plants in early spring. Eggs hatch into dark red, humpbacked larvae with a dark head and two rows of black spots along the sides of the abdomen. Larvae often feed in groups, causing isolated severe defoliation. When the larvae have grown to one-half inch in length they burrow into the soil to transform to new adults that appear in mid-summer and repeat the cycle.
Colorado potato beetle is a difficult pest to control. Hand picking has been used since before the development of modern pesticides. Hand-pick beetles, eggs and small larvae from infested plants as soon as possible (practical for a few insects on a few plants, but impractical for larger gardens and fields). Especially remove overwintering beetles that appear on young plants in the spring.
Another way to avoid severe loss is to adjust planting time. Defoliation of potatoes is most damaging in the period just before and during flowering. Planting either earlier-than or later-than normal allows the potatoes to be in bloom before or after, respectively, the peak of beetle activity. This strategy is most effective when combined with an early-maturing variety.
When insecticide treatment is warranted consider timing, coverage and insecticide choice. Timing is critical. Small larvae are much easier to control and spraying when the larvae are small is much more effective (and required with certain insecticides) than delaying and spraying after the larvae are grown. Early treatment is also necessary to prevent crop loss. Complete and thorough coverage of infested plants is necessary for good control. With that in mind, control is generally more effective with liquid sprays than with dust applications.
Because of decades of repeated insecticide use, the Colorado potato beetle may be resistant to many available insecticides, including Sevin and malathion. Consider other controls available at your local garden store, including pyrethroids and biorational ingredients such as spinosad; Bt tenebrionis, Neem (azadirachtin) and the pathogenic fungus, Beauveria bassiana. Note that the biorationals are only effective against very young larvae; they will not kill large larvae or adults.