The Spider Mite
The spider mite is truly a relative of the spider and therefore not classified as an insect. They are most prevalent in your garden during hot, dry weather. In greenhouses, however, the spider mite can be a continuous pest.
It is important to recognize the early warning signs of spider mites before they get out of control. On roses and other woody ornamentals, the first signs will be a lightening or purplish yellow color change to the upper side of the leaves. This can even be misdiagnosed as downy mildew damage, but a quick look at the underside of the leaf will make all the difference. Spider mites also attack many annuals and perennials.
Crystalline structures note the presence of mites
These mites are so tiny that it may be hard for you to see them without magnification. But if you have good eyesight or good bifocals you will see them on the underside of the leaves. It’s here that they puncture the plant cells and suck the moisture from them. It’s likely you may also see tiny crystalline structures as well as some webbing in extreme cases. They are very active creatures and can quickly defoliate a plant. At the least, these can setback outdoor plants by six weeks. In greenhouse plants, whole crops can be lost.
Spider mite webbing
Spider mite eggs can hatch in as little as 3 days, and new mites can begin reproducing in only 5 days. One female can lay up to 20 eggs per day and can live for up to 4 weeks. Think about that. She is laying hundreds of eggs meaning one female mite could start a population of a million mites in a month or less! This incredible rate of reproduction is one reason mite populations quickly build resistance to pesticides, so chemical control methods can become somewhat ineffectual when the same miticide is used over a prolonged period.
Visible mite damage on rose leaves.
Since insecticides will not kill mites, let’s discuss how to rid your plants of this pest. If you only have a few outdoor bushes, you may want to remove the mites mechanically with a water blaster. Most water wands have a removable nozzle that you can replace with a blasting nozzle. Set the nozzle to a wide pattern but don’t be too conservative. You will need a good deal of pressure. Simply point the nozzle upward and blast those mites off the underside of the bush. In most cases the mites will find an easier target.
Mites on leaf underside.
If the mechanical method is not for you, or if you are growing in a greenhouse, you will need to use a miticide. Miticides have come a long way over the past 15 years and thank goodness there are many to choose from currently. We already discussed how rapid reproduction leads to pesticide resistance. (This is very important to acknowledge.) Almost every miticide label clearly states you should not use the product more than three times a year. For that reason, greenhouse growers and gardeners with many plants will need to rotate two or more miticides in their spray program.
When choosing a miticide, be sure to read the label for products that are approved for your particular crop or cultivar. Some miticides only kill adult mites and this means you would need to spray them twice (initial spray and then three days later) to kill both existing adults and newly hatched mites from eggs. Most modern miticides have incorporated what is called an “ovicide” into their formulations. This means they will kill all stages of mites, including the eggs. These are preferable and most of these newer products continue to work for up to 21 days! Examples are Floramite, Forbid and Shuttle but there are others that are as good or better. There are even a few miticides that are “Translaminar”. This means that the miticide, while sprayed on the top of the leaves, will penetrate through the leaf tissue and to the underside of the leaves. This can be a big help where it is hard to reach the underside of leaves. In almost every case I recommend the use of a good spreader-sticker (surfactant) with your miticide application.
Mite life cycle
Let’s discuss how your plants get mites in the first place. For outside gardens they are simply part of the environment and in hot dry climates you will almost always deal with mites. It’s important to remember that there are many natural predators of spider mites and if you do your best to encourage these (ladybugs, praying mantis, green lacewings etc.) you may be able to eliminate the need for expensive miticides. One way to encourage the good insects is to simply refrain from spraying insecticides. Most insecticides are not selective and kill all insects, even the ones we want in our garden so use these sparingly. If you are growing in a greenhouse environment, you will most likely deal with mites on a continuous basis and a good miticide rotation will be a must!
Finally, be sure to put newly purchased plants or cuttings in quarantine to be observed at least one week for disease, insect, and mite problems. I get many calls each week from growers who discover their favorite miticide no longer works. What I usually find is they have brought new plants or cuttings into their garden or greenhouse without quarantine. The strain of spider mite on the newly purchased plants were already immune to some miticides due to the previous growers’ spray program. Now the new grower has inherited a generation of mites that is resistant to their miticide of choice.
Spider mites, while members of the arachnid family, have little to do with spiders. Spider mites are tiny pests that infest your plants, eat the leaves, and suck the life out of your garden. Their reproductive habits are enthusiastic, meaning a small number of mites can explode into a full-blown infestation in under a month, and also means that they develop quick immunities to the chemicals in pesticides.
They offer virtually nothing of benefit to your garden and leave destruction in their wake. In short, they’re bad news. So how do you get rid of spider mites?
There are ways to deal with them. In this article, you’re going to discover how to recognize spider mite infestations, things you can do to prevent them, and how to deal with an infestation.
- What Do Spider Mites Look Like?
- How to Get Rid of Spider Mites
- How the Mite-y Have Fallen
- Signs Of Common Rose Pests
- Getting Rid Of Spider Mites On Roses
- Symptoms of Spider Mites on Roses
- Controlling Spider Mites on Roses
- How to Get Rid of Spider Mites on Indoor Plants
What Do Spider Mites Look Like?
Common Homes for Spider Mites
- Potted Begonias
- Broad-Leafed Weeds
- Fruit Trees
- Miniature Roses
- Indoor Houseplants
Spider mites are tough to see because they’re tiny. At about 1/20th of an inch in size, they’re invisible to the naked eye unless you’re looking for them, and even then you’ll probably need a magnifying glass. They have oval-shaped bodies and tend to have a pale or reddish-brown color.
You usually find them in hot, dry conditions (above 85 degrees Fahrenheit and with less than 60% humidity) and they prefer certain types of plants over others.
Lacking a magnifying glass, one way to check to see if you have spider mites is by holding a piece of white paper under the plant and carefully shaking the leaves. If you have an infestation, you’ll notice black specks on the paper that resemble pepper.
Evidence of Spider Mites
Chances are, you’ll see the proof of spider mites before you notice the bugs themselves. They’re known as web-spinning mites because you’ll see delicate, milky white, silky webbing on your plants, particularly on the undersides of the leaves.
You may also notice small white, yellow, or brown bite-marks on the leaves. Spider mites eat the chlorophyll in leaves, so you’ll see evidence where they’ve been feasting.
Once you’ve recognized a spider mite infestation, you’re racing the clock. A single female is capable of laying 300 eggs in a few short weeks, meaning their population can explode out of control in a short period.
If you think you have an infestation, check all of the plants in your home, again looking for bite marks in the leaves and webbing. Once you’ve identified which plants are infected, you can turn your attention toward treating them.
How to Get Rid of Spider Mites
Preventing Spider Mites
The easiest way to treat a spider mite infestation is to keep it from occurring in the first place. Luckily, the preventative steps are relatively easy. Here’s how to prevent spider mites on your houseplants.
Water your plants on a regular basis. If you’re taking good care of your plants, you’re probably already watering them regularly. Spider mites prefer dry areas, so a well-watered plant is going to be an effective deterrent.
Additionally, spider mites like warm environments, so using cold water instead of hot or lukewarm water is going to provide an additional barrier against an infestation.
On top of watering your plants, dust them regularly. There are a couple of ways you can take care of dust on your plants, depending on the type and size of your plants.
Plant Care to Prevent Spider Mites
- Clean Smaller or Fragile Plants with a Cloth
- Spray Stronger and More Resilient Plants With a Hose
- Clean each leaf with a cloth. Using a damp cloth is better for smaller or fragile plants. Wipe down each leaf, taking care to clean the tops of the leaves as well as the undersides. Spider mites will often make webs on the undersides of leaves, because they prefer to avoid direct sunlight.
- Spray the plants. Using a sprayer is better for larger and more durable plants. Do this by taking them outside and using a garden hose, or by placing them in a sink or bathtub.
Create a humid environment for your plants. Spider mites prefer dry areas so the wetter, the better. Spray water onto the plants each day. If your plants are small and sit on plates or platters, put water onto the plate to increase humidity.
Keep your plants shaded whenever possible. Plants need sunlight, but consider closing your curtains during the hottest time. If you’re unable to shade your plants, consider investing in a humidifier and putting it next to them to maintain a humid environment.
How to Kill Spider Mites
The first step toward spider mite control is to isolate the infested plants. Start by stripping infected leaves from the plant and either putting them in a sealed bag and throwing them away or burning them. Consider getting rid of the plant altogether.
Spider mites can ride on air currents from one plant to another, so isolate the plants and put them close together to reduce air flow. Water the plants as often as possible to create a moisture-rich environment and if possible, place a humidifier nearby. You want to create as much humidity as possible.
If you cannot isolate the plants, you can still treat them. Make a homemade spider mite killer with a 1:1 mixture of rubbing alcohol and water and spray the leaves. The rubbing alcohol will destroy the mites’ exoskeleton and create an unsuitable environment for them. It also evaporates quickly, meaning the plant will be okay after the treatment.
Types of Predatory Mites
- Phytoseiulus persimilis
- Phyoseiulus longpipes
- Metaseiulus occidentalis
Sometimes, it’s better to fight fire with fire. Introduce certain types of mites to your plants, and they’ll wipe out the spider mites without hurting your leaves. Do a Google search or take a trip to your local nursery and ask about predatory mites.
The process is easy and straightforward. The predatory mites will start by eating the spider mites. Once the spider mites are gone, they’ll cannibalize each other and wipe themselves out, making them useful and self-contained biological controls.
Natural Remedies for Spider Mites
A frequent error gardeners make is that they attempt to use pesticides to treat spider mite infestations. Avoid using pesticides. Spider mites develop quick immunities, so what you’ll end up doing is killing the insects that prey on the spider mites.
In short, chemical pesticides encourage spider mite infestations. So what’s the best way to kill spider mites? To treat spider mites naturally, try the following techniques.
On its own, rosemary oil is effective against spider mites because it attacks their nervous system. Blend rosemary essential oil with water, or buy a rosemary-based pesticide. Rosemary is known for deterring spider mites, and it is not harmful to the plant or beneficial predatory insects.
One of the best aspects of rosemary oil is that it works in tandem with biological controls. Rosemary will deter spider mites, but it has no effect on the predatory mite Phytoseiulus persimilis. As with many essential oils, rosemary oil is also an excellent remedy to repel and keep spiders away.
If you’re having trouble with multiple types of insects on top of spider mites (such as aphids, ants, and ticks), mix a solution rosemary oil, peppermint, thyme, and clove for an all-purpose, all-natural insecticide. Again, predatory mites are resilient to natural oils, meaning you can apply the solution without hurting them.
Neem Oil Spray Recipe
- Neem Oil (2 Tbsp)
- Dishwashing Detergent (1/3 Tsp)
- Warm Water (1 Quart)
Neem oil is excellent at deterring pests like spider mites. As long as you use neem oil correctly, you can get safe, natural results. Ideally, spray the plants in the evening so that they will stay dark for at least five hours.
Neem oil can be sprayed every three days for three weeks until the spider mites are gone. If you’re making the solution at home, mix neem oil into water. You can also buy pre-made neem oil solutions at most gardening stores.
Spider Mite Soap Recipe
- Non-Detergent, non-degreaser Soap (3 Tbsp)
- Warm Water
- Cold Water
- A Tablespoon
- 1-Gallon Jar
- Spray Bottle
Soap is a mild, effective means of taking care of spider mites. Soap covers spider mites and suffocates them.
Start by adding liquid dish soap into a 1-gallon jar. You’ll want to go for a mild soap, avoiding detergents and anything with degreaser as an ingredient. Fill up the rest using warm water. Shake the jar thoroughly until the solution is well blended with the water and pour into a spray bottle.
You might consider testing the solution first, to make sure that the soap isn’t going to hurt the plant, by applying the solution to a small section before committing to treating the plant in its entirety.
Apply the solution directly to the mite infestations. You want to saturate the mites thoroughly, and the leaves should be well-doused. Take care to be detailed, spraying each leaf individually instead of the entire plant. Avoid spraying the strong parts of the plant.
Allow the solution to set for two to three hours, which will give the spider mites time to die off. At the end of the three hours, clean the soap from the plants using cold water.
Throw away whatever soap solution remains. Instead of keeping it, make a new batch each time you want to spray for mites. Apply the soap solution about once a week until the infestation is gone.
Characteristics of Good DE for Plants
- Meets Food Codex Standards
- < .1% Crystalline Silica
Diatomaceous earth is the fossilized remains of tiny ocean plants called diatoms. DE is dust that looks like flour, and it’s extremely dangerous to spider mites because it desiccates them until they die. In other words, DE has a property that causes it to suck up liquids and fluids.
It eats away at the spider mites’ cuticle’s outer layer, making it impossible for spider mites to maintain the fluid levels necessary to keep them alive. They dry up and perish.
While searching for DE to use, keep an eye out for a couple of things. You’ll want a DE that meets Food Codex Standards (which means it’s safe for you to handle) and has less than .01% crystalline silica.
Avoid using pool grade DE, because it’s loaded with crystalline silica and is dangerous to breathe.
DE isn’t an end-all-to-be-all for infestations, and you’ll probably want to incorporate other tactics on top of it, but by dusting your plants with DE consistently, you help to prevent the spider mites from infesting in the first place.
Pyrethrum, made from the pyrethrum daisy, is an organic pesticide and contact killer. It’s a nerve agent, meaning you spray it on the mites and they first become paralyzed, before dying.
Will it work? Yes.
The trouble is that, much like with pesticides, it’s toxic to virtually all insects. Unlike with pesticides, you will kill the spider mites, but you’ll also kill beneficial insects that pollinate your plants and otherwise keep them healthy.
How the Mite-y Have Fallen
Spider mites can be tough to get rid of, but luckily there are plenty of ways you can handle them. If you’re dealing with an infestation, keep at them.
Try different techniques and figure out what works. When you finally get rid of them, use the suggestions above to keep them away for good.
In this article, you learned how to get rid of (or kill) spider mites and some natural remedies that will help you do so.
Have you noticed spider mite webbing on a friend’s plants? Is a family member of yours dealing with an infestation and feeling overwhelmed? Use the buttons below to share on Facebook, Pinterest, and Twitter.
Signs Of Common Rose Pests
Some pests specifically target roses. You can help protect plants by inspecting them a few times a week. Pests reproduce quickly, though, so you want to be sure you recognize the symptoms of a problem before it becomes a major headache. Use our guide to sharpen your pest-spotting skills.
These sucking insects show up early in the season, before the first rose ever opens. Oval-shaped, small and light green or pinkish, Aphids are easy to overlook. They reproduce rapidly, which is why one day your roses look fine, and the next day stems appear alive with movement.
Aphids suck the juices out of new shoots, buds and leaves. They produce honeydew, a sweet, sticky substance that hosts Black Sooty Mold and attracts Ants. If you miss the bugs clustering along new growth, you may see Black Mold or possibly Ants racing up and down stems.
Other signs of Aphids: curled, stunted or puckered leaves; yellowing leaves that fall from stems; misshapen blooms with streaked petals
Two kinds of Inchworms affect roses: the Fall Inchworm and the Spring Inchworm. They’re actually Cankerworm Caterpillars. Both types hatch in spring when air temperatures hit the 50ºF mark.
You’ll typically spot them on unopened rose blooms, inching along petals, munching as they go. Infested roses are usually located beneath trees. The worms drop from the trees to the roses.
Other signs of Inchworms: misshapen blooms with streaking on petals; edges of unopened buds are rough and nibbled
Several types of Sawflies attack roses. These pests look like Caterpillars but aren’t – and they’re not Slugs, either. That means you can’t treat them using traditional Caterpillar or Slug controls. They’re about ½ inch long and move like an Inchworm.
Sawfly Larvae frequently feed along leaf undersides, sucking out the green parts and leaving a transparent, papery spot. Larvae feed for about four weeks before pupating. If you spot damage early and identify the culprit, you can treat. Depending on which Sawfly species is present, you’re facing one to six generations per year.
Signs of Rose Slug Sawfly: holes or papery spots appear along leaf midribs, then move toward leaf edges; skeletonized leaves
Cottony Cushion Scale
Scale insects lay eggs on rose stems in fall. Eggs hatch in late spring, and the young Scale insects prowl along rose stems, seeking a spot to latch on and start sucking. The surest sign of Scale is white, circular, limpet-looking things on rose stems. In early spring, egg cases are visible as white cottony masses.
Scale feeding produces honeydew, which attracts Ants and may grow Black Sooty Mold. Plant surfaces become sticky in a severe infestation.
Signs of Scale: stems encrusted with small white circles; sticky plant surfaces; Ants crawling up and down stems; Black Sooty Mold growing along stems
When Thrips are present, you get brown, streaky buds that only partially unfurl. Thrips are tiny (1/16 inch long), slender sucking insects that are usually yellow, brown or black. They’re very difficult to see. Normally you have to shake a bud over a piece of white paper to spot the insects.
Thrips typically infest roses when conditions are hot and dry. If an unseasonal spring heat wave arrives, watch for Thrips. Otherwise, they usually appear as summer arrives. They prefer light-colored blooms in shades such as pale yellow, white or light pink.
Signs of Thrips: flower buds don’t open; petals have brown streaks; petal edges look ragged and brown; infested flowers that open are distorted
You’ll also see beneficial insects in spring, including Ladybugs, Green Lacewings, Spiders and Praying Mantises. Don’t disturb or discourage these critters. They’re your partners in controlling pest outbreaks – not just on roses, but in your garden.
Image UGA5082075: Whitney Cranshaw, Colorado State University, Bugwood.org
Image 5439081: Joseph Berger, Bugwood.org
Image 5429886: Brian Kunkel, University of Delaware, Bugwood.org
Image UGA1482004: Sturgis McKeever, Georgia Southern University, Bugwood.org
Image 1476101: Whitney Cranshaw, Colorado State University, Bugwood.org
Getting Rid Of Spider Mites On Roses
By Stan V. Griep
American Rose Society Consulting Master Rosarian – Rocky Mountain District
Spider mites can be tough customer pests to deal with in the rose bed or garden. One of the reasons that spider mites become a problem in the garden is the use of insecticides that kill their natural predators. One such insecticide is carbaryl (Sevin), which pretty much wipes out all natural predators of the spider mites, making your rose bush a virtual playground for these annoying pests.
Symptoms of Spider Mites on Roses
Some symptoms that spider mites are at work on your roses would be discoloration or bronzing of the leaves/foliage and scorching of leaves. Left untreated, foliage injury can lead to leaf loss and even the death of the rose plant. When the spider mite population on roses is high, they will produce some webbing on the plants. It will look like a rose with spider webs on it. This webbing provides them and their eggs with some protection from predators.
Controlling Spider Mites on Roses
To control spider mites by chemical means will require what is called a miticide, as few insecticides are effective against spider mites and many can actually make the problem worse. Most miticides will not actually get to the eggs so another application 10 to 14 days after the first application will be required to gain control. Insecticidal soaps work well in controlling spider mites too, just as in the control of the tent caterpillars, but will typically require more than one application.
A key note to make here is that no insecticides or miticides should be applied to rose bushes or other plants during the heat of the day. The cool of the early morning or evening are the best times for application. Another very important rule is to make sure the plants and bushes have been well watered prior to the application of any pesticide. A well hydrated plant or bush is far less likely to have an adverse reaction to the pesticide.
Green lady bug? Nope.
Why am I showing holes in the rose petals?
If this picture is too sad– look no further. If you are squeamish– turn back.
This is a bad bug rose post– a visual introduction to help you identify who might be harming your roses. I’ll tell you about my personal experience, and then I’ll defer to Nanette Londeree, Connie Hilker, and Baldo Villegas, and their accompanying links, for more details.
The three shots directly above illustrate rose curculio and its damage. The top guy is a cucumber beetle.
I never use pesticides– their use is far more damaging to the environment than it is to the bugs.
Each morning, and beleive it or not, almost each afternoon during curculio season, I’m on a search and kill mission. At this point, a few still linger– I want them gone so bad. Thankfully these bugs are slow movers, and with concentration it’s pretty easy to catch and flatten them between two fingers. They are crunchy, not squishy. You can also carefully scoot them into a can of soapy water or alcohol, but that’s too complicated for me.
Damaged buds and blooms should be discarded for they shelter eggs for next year’s hatching.
This many curculios, in a small space, is a sure sign of infestation. For two years in a row, almost all my Rugosa Rubra buds were mortally wounded. I cut the shrub to the ground mid-infestation last year (just after this shot was taken). This year my rugosa had a few of the little monsters, but nothing remotely like last year. In the past, I’ve uprooted a large Nutkana and an even larger Eglantine that had bad invasions. If sizable shrubs come under attack, I figure it’s just too risky to spread the madness. Out they have to come.
Click here and here for more information on the rose curculio.
In Washington D. C. I finally saw these fascinatingly beautiful (yet damaging) creatures for the first time.
Connie Hilker at Hartwood Roses, in Fredricksburg, VA sent the gorgeous images above and writes: Japanese beetles eat flowers and leaves, and they can defoliate a small plant if we let them. To keep their numbers down, you go out in the early morning and knock the beetles into a jar of soapy water or rubbing alcohol. Some of my rose friends squish them by hand– that’s a bit too icky for me, however. Don’t be tempted by the promises of beetle traps. The traps contain powerful attractants that lure more beetles into your garden than the trap can catch. Those that miss the trap will find your garden instead.
I don’t know much about hoplia beetles, but I saw some in Grass Valley recently, and I hear they go for the roses in Sacramento. Jan Hedman kindly sent me the picture above.
Spit bugs are comic relief compared to the baddest bugs. In my garden, they come in early spring and tend to be on just about everything. They might distort growth for a while, but the plants quickly grow out of it. The bubbles are amusing and the bugs are kinda cute, but spit is spit and not too impressive when guests are expected. Water spray, a few days in a row, does a good job. They generally leave in the middle part of the first bloom period.
Salvia Greggii does not escape spit bugs.
STAMEN EATERS !
I just want you to know, little guy, it’s going to be a long time before you find any stamens on that Pilgrim bloom.
Yeah, stamens on singles (5-petal roses) are your favorite diet.
These bug are rampant in my garden this year– right this minute– they are everywhere! They move faster than curculios and they are NOT crunchy. It’s a matter of being irritated by them– damage ruins the flower after it blooms, not before.
They so give me the creeps. Almost every bloom on our Soaring Spirits rose fell prey to these travelers from India. Squishing them between flower petals is the only way I can manage with them– I’m squeamish even looking at the picture. These crickets are not a major problem anywhere else in the garden. Oh I want to finish this post!
Earwigs love stamens too, but they are not a big problem here either.
Such a drama worm– what a photo op tomato worms are. No guy, it’s not a tomato. There are never too many of these green wonders, but they do take some big chunks out of a rose bud.
Thrips and spider mites are other bugs that bother roses, but I don’t really have experience with them. Cane borers do damage, by wilting part of the cane they inhabit. Snapping the cane a little past the wilted part seems to be helpful.
PS 8/23/2012– since writing this post, I’ve had spider mite issues in my own garden and a client’s. First of all the mites are microscopic. It’s kind of weird how I finally knew I had them. All the roses kind of gasp and look dry, spidery webs appear here and there and leaves become sort of spotted, brownish, not themselves. I know this sounds too subjective, maybe a reader has a better discription. The remedy can be quite dramatic. Apparently spider mites hate water. Douse, I mean drench the roses and yourself, with water from your trusty hose, and be sure and spray from under the bush, and of coarse from the top and all around. Spray again and again on the first day, and again and again on the next day. Your roses will thank you and you will definitely be able to tell how happy they are to be releived of spider mites. Two sprayings should do the trick.
I don’t have a lot to say about aphids. My roses are affected by them, but soldier beetles and lady bugs keep them in check. You’ll find out more about them on my GOOD BUGS post.
I’ve never been so relieved to finally finish a post. Even though I can’t stand some of these critters, I do like photographing them, and this post has been a labor of love that I hope is helpful.
I know lady bugs eat aphids, but I rarely see them in action. I found this image, by Isabelle Breguet, on FB last week. Isn’t it beautiful? She has more wonderful images on her blog.
Thank you so much to all the contributors to this post !
GOOD BUGS FOR ROSES–
How to Get Rid of Spider Mites on Indoor Plants
Ladybugs and praying mantis will also keep your plants safe if you place them in your small-sized grow-space. Understandably, it doesn’t sound feasible or wise to invite any insects, even beneficial, inside your home.
So, to keep spider mites at bay and protect your houseplants, you can grow pest-repellent plant varieties, such as Chrysanthemum, dill and coriander. Companion plants, of course, are more of a preventative measure and won’t do much if your entire greenhouse strawberry crop has been infested with the nuisance pests.
Insecticidal soap. You can easily make a homemade insecticidal soap by diluting a spoonful of mild dishwashing liquid in a couple of litres of water. Spray your plants with the solution, which will suffocate any adult spider mites. The pesticide is not as effective against their eggs, however. So, you’ll need to repeat the treatment in a few days.
Tobacco. A natural pesticide that controls these garden pests can be made of tobacco and water, as well. To make a homemade spider mite spray, soak a handful of tobacco in a cup of water overnight, strain through a sieve and dilute the liquid in two litres of water.
Chamomile. Not as an effective spider mite killer on its own, but when mixed with sulphur, which has very low toxicity to humans and pets, you can make a solution with water and spray your indoor plants.
Note that you can treat a single houseplant, for instance, with just pure water. Wipe the leaves or wash the plant under the tap or shower to kill off any spider mites on it.
As spider mites like a dry and hot environment, raising the humidity level in your grow-room/greenhouse will affect adversely their ‘well-being’. You can resort to daily misting or water-spraying, as long as the plants you grow can tolerate humid conditions and are not susceptible to fungus infections.
Not a very popular control measure but growers can also use a hand-held vacuum cleaner to remove manually the pesky pests from their plants.
Other non-chemical miticides
If you wonder how to get rid of spider mites during flowering, there is an effective organic acaricide, which may help you in the quest. Purchase a product that contains pyrethrin from any organic garden pesticide store and read carefully the label instructions before proceeding with the application.
Derived from certain Chrysanthemum species, the substance is toxic to insects. Note, however, that beneficial insects will be also affected if you intend to use it outdoors. Furthermore, it can cause skin and respiratory reactions in people, and especially kids, so keep the product out of children’s reach and use with caution.
Neem oil is another organic substance (of low toxicity), which you can use as a repellent rather than a solution to your spider mite problem.
A mixture of 2% rosemary oil and water can also reap successful results with moderate infestations.
The most effective chemical insecticides that can be useful against spider mites, as well, are two synthetic pyrethroid substances, called permethrin and bifenthrin. Both match the properties of the above mentioned natural pyrethrin but differ in their susceptibility to UV light and changes in pH.
Again, their application may be contraindicated indoors if you have young children or allergic family members but can be used to treat plants grown in a greenhouse. Apply carefully and bear in mind that spider mites may become resistant to the product over time, due to their short life cycle, which prompts growers to repeat treatments excessively.
How to prevent a spider mite infestation
Surely, prevention is always better than cure, so here’s what you should know, in order to keep your plants spider mite free.
Spider mites can ‘hitchhike’ on your clothing or shoes after an innocent visit to your local garden centre. So, always ensure that you change your clothes and footwear before checking on your established greenhouse crops.
Always isolate a newly purchased plant for a few days before placing it together with the rest of your blooming houseplants. This way, you can act swiftly if you spot a problem and treat the plant before it infects other varieties in your indoor garden.
- Environment management
Keeping your plants well watered and healthy by using mulch and compost may help them stay less prone to pest infestations. Furthermore, large indoor grow areas should have an effective air filter system in place to prevent spider mites from entering from outdoors through the vents. Hosing your greenhouse plants with water (or spraying individual houseplants) is also a good preventative measure.
Monitoring regularly your plants for signs of spider mite issues is a guaranteed method to keep them pest free. This way, you’ll be able to spot the signs and remove any affected leaves and branches in time. Then, treat the plant with one of the discussed methods in this post.
Hire a Professional!
Need help with erradicating spider mites? Book a professional gardener.
Image source: /Jonathan Oscar
- Last update: January 29, 2020
Posted in Pest Issues
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Organic Strategies for Two-Spotted or Spider Mite Control © Frances Michaels
With their common use of compost and mulch, organic gardeners have a head start in the control of this chlorophyll-munching mite.
Mites secrete a very fine, silk-like webbing which protects them from enemies and chemical sprays. When large populations have been present for a few weeks, webbing may cover the whole plant. Females leave plants via threads of webbing blown on the wind, or they may drop off a plant and crawl to a new plant. Female two-spotted mites over-winter in the soil under leaf litter, tree bark, or cracks in greenhouse walls, emerging in late spring to lay eggs. At a temperature of 30°C their life cycle can be completed in 8 days, giving 12 to 20 generations over summer. Mite numbers build fastest in hot, dry weather with low humidity.
Organic gardeners have an advantage regarding spider mite control. Common organic practices such as making compost, mulching the soil and avoiding chemical insecticides help to encourage predatory mites, a major killer of two-spotted mite. A healthy garden will have a resident population of predatory mites to keep pest mites under control. Predatory mites are abundant in the top layers of soil, in humus and animal manures.
Two types pf predatory mites are available commercially from www.goodbugs.org.au – Phytoseiulus persimilis and Typhlodromus occidentalis. They are best introduced when pest numbers are low.
Phytoseiulus persimilis are available from: Bioworks (NSW); Biomites (Qld); Manchil IPM Services (WA); and as part of the OCP Backyard Buddies range.
Typhlodromus occidentalis are available from Biological Services (SA).
Gardeners who commonly spray insecticides to control caterpillars and other pests risk killing off the natural enemies present, as predatory mites are very susceptible to pesticides. Research has also shown that certain insecticides stimulate mite reproduction, so the gardener may have controlled one pest only to find that the population of a much more serious pest, the two-spotted mite, has exploded. In this case, the organically acceptable caterpillar control, Bt ( Dipel), would have been a much better choice as it would have not affected the beneficial predator at all.
Physical and Cultural Controls
There are some easy things you can do that will have a big impact on spider mite numbers, keeping in mind that spider mites prefer high temperatures, low humidity and dusty conditions.
- Try a high pressure hosing in the early morning – three days in a row.
- Hosing plants mid-season to remove dust on the leaves helps too.
- An unlikely pest control device is a hand held vacuum cleaner! After vacuuming, tip the contents immediately into a plastic bag and place in the freezer for a few hours. You can control whiteflies doing this as well.
- Pruning affected plants and removing infested leaves will reduce pest numbers.
- Try to control weeds that harbour the pest such as plantains, black nightshade and marshmallow.
- Keep your plants healthy by feeding, mulching and watering.
Least Toxic Chemical Controls
Two-spotted mites are not insects and are highly resistant to many chemical insecticides. There are several organic controls that work well, as their mode of control differs from that of a chemical insecticide. Mites are mostly found under the leaves, so spray and coat this area particularly well. Due to the very fast development time of this pest, especially during warm weather when eggs are laid continuously, it is important to carry out repeat spraying if recommended.
- Potassium soap sprays such as Natrasoap or Nature’s Way Vegie and Herb Spray are a good choice of control for the home gardener. Soap sprays work by blocking the mite’s breathing pores and dissolving its outer covering, resulting in dehydration. They are considered very safe for the environment.
- A horticultural oil such as Eco-Oil can be very effective in smothering the mites and mite eggs. Avoid using it at temperatures higher than 35°C as it may cause leaf burn. A follow-up spray 3-5 days after the initial spray application is usually needed. Eco-Oil is certified organic, made from botanical oils and has an enhanced formulation which helps to attract beneficial insects to the garden.
- Neem is a botanical insecticide made from extracts of the neem tree. Eco-Neem is a registered organic spray that controls a wide range of insects and mites including spider mite. It works in multiple ways with the two main actions being suppression of insect appetite (they starve to death) and restricting growth (unable to moult successfully). It is approved in Australia for use on ornamental plants only.
- Wettable sulphur or dusting sulphur can only be used in cool weather, or it will cause leaf burn. You should avoid using an oil product for at least a month after applying sulphur because in combination it can cause phytotoxic problems for plants.
Research has shown that a 2% rosemary oil solution can kill mites, without harming the beneficial predatory mite. Make sure to always dilute the oil prior to spraying it. To make 1 litre of spray, use 980 ml of lukewarm water with 10-20 ml (2 – 4 teaspoons) of rosemary oil. Adding a teaspoon of castile soap (soap made of olive oil) to the solution will help it stick. Always test a small area of leaves before spraying the whole plant and never spray in very hot weather. A range of other plant extracts, including garlic extract, clove oil, mint oil, eucalyptus oil and cinnamon oil have also been found to be effective.