Milky spores for grubs

Grub Worms

Grub worms are one of the most common pests that invade vegetable gardens. If you are not familiar with them, they are those white or gray little creatures that munch up the roots of your vegetable plants.

What is a Grub Worm?

The grub worm is not exactly a worm, like your friend the earthworm. Grub worms are Japanese Beetle larvae, or the babies of those beetles. Unlike earthworms that fertilize your soil to make your plants and flowers healthy, grub worms ruin them by munching on the roots of your plants, flowers, and grass in your lawn or garden.

A healthy lawn can handle a few grub worms in the soil and will do little or almost no apparent damage. After the eggs of the Japanese Beetle hatch and turn into larvae, they tunnel underground and start eating roots they see.

However, when there are more than 15 to 20 grub worms per square foot in your vegetable garden, then that is a real problem. You surely will notice that you have a grub worm problem when the condition of your lawn or garden radically deteriorates.

Signs of Grub Worms

Grub worms are real pests and can cost you a lot when they damage your favorite (and expensive) plants and flowers.

Even though here at Veggie Gardener, we are mostly concerned with the well-being of our vegetable garden, there is still the need to check the overall lawn as well. If you have grub worm issues in the lawn, then you most likely will have them in the vegetable garden as well.

Here are some of the common signs of grub worm infestation of plants or lawn:

    • Droopy leaves
    • Green-gray or brown patches on your lawn
    • Grass easily “peels” off
    • Ground feels spongy to the feet
    • Sudden death of plants, grass, or flowers
    • Appearance of moles, armadillos, or other pests in your lawn

Why You Should Get Rid of Grub Worms

Grub worms feed on the roots of plants and the other things planted in your garden. Such actions severely affect them and eventually lead to wilting, or the death of these plants.

Roots of plants are very important organs. They are the ones responsible of absorbing water and other essential nutrients from the soil to make the plant grow. With them damaged or eaten up completely, the plant has no other means of absorbing nutrients and water from the soil.

When the roots are damaged, it may not be able to absorb the water and nutrients the entire plant needs to function properly, that is why you see your plants, flowers, and your grass droop, turn brown or gray, and eventually die.

Aside from damaging your garden, when there is a serious grub worm infestation, it will attract other animals or pests that feed on them, making the problem even more serious.

Examples of such creatures that eat grub worms are armadillos, gophers, and moles. Though these creatures eat grub worms, they leave nasty burrows and instantly damage your lawn or garden.

How to Get Rid of Grub Worms

Beetles usually lay their eggs during early summer. After these eggs hatch, they turn into nasty pests, known as grub worms. Grub worms then tunnel underground and feast on the roots of plants and grasses until the winter or fall season.

If you will notice, this sort of problem is like a cycle and it seems that there isn’t a permanent solution to get rid of them.

It is a cycle because these grub worms will soon mature and turn into adult beetles, and again, laying eggs in your lawn or garden that soon will become grub worms.

There are several ways to get rid of grub worms, but you must know that there is no permanent solution, nor a feasible plan to prevent them from coming back. The key here is being vigilant and knowing when the beetles in your area start laying eggs.

Surely there are pesticides that you can purchase and use.

However, you might want to steer away from such chemicals if you have children or pets, or when you eat the ones you plant in your garden or yard.

A lot of people prefer the natural means of getting rid of these pests, there is no need to invest on expensive pesticides. All it takes is a little patience and time.

Natural Solutions For Getting Rid of Grub Worms

Here are the steps to rid your lawn or garden of these grub worms naturally:

You already know you have a grub worm problem, now you have to determine when the beetles start laying their eggs. You can surf the Internet or call your local cooperative extension office to ask such information.

Beneficial nematodes (plant parasitic nematodes are bad for vegetable garden plants, you can visit the Nematodes page to read about them) are the natural enemies of grub worms. They infest and kill these pests. However, they are only effective on young larvae.

This is where your research will come in. Once it is the season of beetles to lay their eggs, purchase nematodes from a gardening store and follow the instructions indicated. Spray on your lawn or vegetable garden.

Using milky spore on your lawn is another natural way to kill grub worms. Just spread on your lawn and milky spore can kill grub worms for up to 10 years.

To offset the damage caused by the grub worms, keep your vegetable garden or lawn watered. Abundant water will help the damaged roots easily absorb water.

Robins and other songbirds love grub worms. Have them in your vegetable garden and you will have to worry less about those pests. This is probably the best long-term solution you have. Encouraging these birds to your garden area is recommended to reduce grub worm populations.

Grub worms are serious pests especially to those vegetable gardening enthusiasts. These solutions will help you get rid, or at least keep the grub worms under control. You don’t have to worry about contaminating your garden with chemicals since you won’t need any at all.

All Natural Products For Eliminating Grub Worms!

Having grubs in your lawn or garden can be a right pain in the proverbial backside. Just knowing they are there in the first place if difficult, as the signs of having grubs can be very similar to other common problems.

And when we do know that they are there – how do we get rid of them?

Knowing how to get rid of grubs starts with having a little information under your belt, so you know what you’re looking for and the best approaches for defeating these lawn-killing pests.

Disclosure: As an Amazon Associate I earn from qualifying purchases. However, this does not impact our reviews and comparisons. All opinions are our own we pride ourselves on keeping our articles fair and balanced. For more info see our disclosure statement.

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What Are Grubs?

First of all, what are “grubs”? It’s a pretty general term and can refer to a number of different kinds of thick, worm-like beetle larvae that live in your garden soil.

They exist as dormant eggs through the cold winter months, and then hatch in the spring to burrow around and eat the roots of your plants.

Eventually, they will change into their adult forms and lay more eggs that hatch into next season’s grubs, starting the cycle all over again.

Some species can take more than 1 year to complete the cycle, but the idea is the same.

How to Identify Them

So how do you know you have grubs? Your first signs are likely going to be problems with your grass and other plants. Odd patches of grass will start to die off and turn brown, without any apparent cause. If you do have a grub problem, the damaged grass should pull up easily since the grubs have been eating away the roots underneath.

Once you can see the dirt, you should have a clear view of any grubs. They don’t burrow too deeply Depending on the specific species (we’ll get to that in a moment), they’ll be an inch or so in length, cream-colored with a dark brown head, and usually curl up in a “C” shape when the sod is pulled off.

larvae of the European Chafer beetle. By David Cappaert, Michigan State University, , via Wikimedia CommonsAnother tip-off that you have a grub problem is the increased activity around your yard from raccoons, skunks or birds. These animals love to eat grubs, and will come in droves for the easy snacks. So finding patches of sod all torn up and dug through can mean you have grubs, even if they’re not the ones who directly did the damage.

For more specific species identification, it gets a little tougher. We’ll discuss the different kinds of grubs in the next section.

Types of Grubs

In North America, you’ll likely be finding grubs from a few different families of beetle. June beetles (also called June bugs or even May beetles) are the most widespread, but you may also have Oriental beetles or European chafers. They all look very similar when in the grub stage and most home gardeners aren’t going to be able to tell one from the other without a little research and possibly an insect identification guide.

While technically there are some species of grubs that are harmless to your grass, most will be a problem. If you see grubs in the dirt without any actual damage going on, you might want to wait and see what develops before you reach for the insecticide.

How To Get Rid of Grubs

Now we can get to the important details on how to get rid of grubs. You have two general options: pesticides or a more natural route.

One point to mention before you go to war on the grubs, they are a natural part of the ecosystem and you shouldn’t necessarily worry about them unless there are large numbers. If you check under the grass for about a square foot, and only find 5 or 6 grubs, then you can just leave them alone. They aren’t going to cause much of a problem.


For commercial pesticides, you have a few choices. Most will come in either liquid or granular form, and can contain compounds like carbaryl, imidacloprid, or halofenozide. These are known as “curative” products as they are designed to kill existing grubs.

You’ll have to check with the instruction on the how and when to apply because not all products target grubs at precisely the same stage. That means some may be put out on the lawn later in the season than others. Check the labels.

Some products can deceive you into thinking they are effective against grubs by showing a grub on the packaging when they actually do not kill grubs at all. Be sure to read the instructions on the packaging to ensure you are buying a product that will actually work.

Take note that even though chemical products might seem more effective, they will kill a lot more than just the grubs. That can have a negative effect on the health of your lawn since there are so many beneficial insects living down there as well.

I have had great results with Bayer Advanced Grub Killer. Give it a go!

BioAdvanced 700740M 700740S 24-Hr Grub Control, 10-Pounds

  • Excellent turf Rescue formula – Kills grubs overnight
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  • Kills grubs in 24 hours
  • Treats 5, 000 Square feet

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Natural Options

If you want ideas on how to get rid of grubs naturally instead, there are effective ways to take that approach.

One of the most popular is to introduce parasitic nematodes into your lawn, which can be purchased online or at garden stores (they’re alive, so buy right before you plan to use them). They sound a little scary but they are just microscopic organisms and are harmless to anything but a grub.

Milky spore is another natural bacteria that can help if you are dealing with Japanese beetle grubs specifically.

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Another simple way to kill off grubs is to let them dry out. They only thrive in moist soil and will die during a drought. Avoid watering the grass and you might find that is enough to kill them. Granted, it may not be the best choice for the grass but many species of grass will bounce back after a dry spell.

Timing can be important too. Spring and early summer can be the best time to target a grub infestation, as they are the most vulnerable then. Once they are in their hard pupae casings, they are much harder to kill. And of course, when they are in their adult phase, they aren’t under the ground any more and will require different tactics.

Still Got Grubs? Don’t Worry

While pesticides and natural methods can get rid of the majority of grubs, it is inevitable that some will remain.

If you find a grub here or there when working in your yard, don’t stress too much. It is highly doubtful that you will ever be 100% grub free.

As long as there are no signs of problems, you can rest easy.

Bonus Info: A Little Prevention

Sometimes the best way to get rid of lawn grubs is to keep them out of your soil in the first place. That means targeting the adult beetles before they have a chance to lay their eggs. When they are in their adult beetle form, they are dealt with just like any other above-ground garden bugs.

Usually, a standard insecticide will work. Even a natural repellent with pyrethrins can be enough to deter the beetles from spending time in your yard and laying their eggs. You can even go old-school and use the pick-and-crush method to kill off any of the large beetles you see in your yard.

If you can’t get a handle on your grubs this way, there are also commercial preventative products you can buy that contain many of the same chemicals as the grub-killers. These are intended to either kill/repel the adult beetles or kill the eggs before they hatch, and are labelled as “preventative” control products (as opposed to the previously mentioned curative products). A popular choice of grub preventer is Grubex – you can find it on Amazon here.

So next time you have to deal with lawn pests, now you know how to get rid of grubs.

Pricing last updated on 2020-02-01 at 23:24 / affiliate links – Details

How to Get Rid of Garden & Lawn Grubs Naturally (Guide)


Before we get into how to get rid of grubs in your lawn or garden, we should first take a look at what a grub is and why they are destroying your lawn in the first place.

Grubs – also called white grubs, grub worms, or lawn grubs – are the larvae of scarab beetles, such as Japanese beetles and June bugs. The basic cycle consists of beetles laying eggs in late summer and fall, those eggs hatching into larvae that burrow into the soil and survive on organic matter (like roots) through winter and spring, and then the larvae entering the pupal stage and maturing into beetles to leave the soil in late June. Then, after dining on foliage for the summer, the new beetles lay another round of eggs, and the process starts over again.

Why Are Grubs Bad?

A large grub population can decimate a vegetable garden, flower bed or natural grass lawn, but most serious grub issues that homeowners deal with have to do with their lawns. While a small population (fewer than five grubs per square foot of soil) is generally not an issue and will not destroy your grass, a population of 10 or more grubs per square foot can cause significant damage.

The damage caused by grubs is largely due to their diet, which consists primarily of grass roots, as well as other organic matter in the soil. As they eat the roots of your grass, they destroy the root system, which means your grass will not get the water and soil nutrients it needs to stay healthy. This will lead to patches of grass that are brown, dead and easy to pull out of the ground.

A significant grub population can also lead to lawn, flowerbed, and garden destruction indirectly as birds, raccoons, and other grub-eating critters tear up your lawn or garden to get to the grubs.

How Do I Know if I Have a Grub Problem?

Most homeowners discover they have grubs in their flowerbeds or vegetable garden when they are digging the soil for spring planting or fall garden cleanup. For folks who find grubs in their lawns, most discover the issue while investigating oddly shaped, brown patches of grass in one or more areas of their lawn.

These patches are most often found in spring or in late-summer and early-fall, which are the seasons when grubs are most active. During the winter, grubs burrow deeper into the ground, and then move back to the top few inches of soil in the spring to eat and become pupae to emerge as beetles in early summer.

Alternatively, homeowners may discover their grub problem after they notice that racoons or birds are tearing up their lawn and that what they are uncovering are not run-of-the-mill earthworms.

In some cases, you may notice sections of your lawn that feel spongy. This can be an early sign of a grub infestation that may appear before brown patches develop.

If you suspect that you may have a grub problem in your lawn, the easiest way to investigate is to try to pull up the brown patches of lawn. If they easily lift or peel away from the soil, this means that the root system has been damaged, and you likely have grubs.

Since this area of your lawn is already damaged, go ahead and remove some of the patchy grass so that you can dig down into the soil. In the winter, the grubs will be deeper in the ground, but in the spring, late summer or fall, they will be in the top few inches. Dig up about one square foot of turf in a few areas to see how many grubs you have per square foot.

If your lawn is otherwise healthy, it should be able to sustain a population of nine or fewer grubs per square foot. If your lawn is not in optimal health, it can only sustain a population of five or fewer grubs per square foot. This means that if you have a population of five or fewer grubs, you do not need to treat it, but if you have population between six and nine per square foot, you will need to consider the overall health of your lawn when determining whether you need to treat it.

If you have visible damage and a population of 10 or more grubs per square foot, you will need to treat your lawn to avoid additional damage.

While most lawns can survive with a small population (fewer than nine per square foot), you may want to treat it anyways if animals are digging you your yard trying to get to the grubs.

Bonus Tip: Keep an eye on your neighbors’ lawns. If you do not think you have a grub problem but it looks like they might, you may want to take preventive measures to avoid their grub problem moving onto your property.

How to Get Rid of Grubs Naturally

If you decide to treat your garden beds or lawn for grubs, it is best to introduce the treatment to the soil in mid- to late-summer or early fall. During this time, the grubs will be newly hatched and will be near the surface and beginning to feed. During the winter, they burrow deeper into the soil, and during the spring they are in the pupal stage, and then move into the imago stage, which means most treatments will be far less effective.

Many beetles return to the same area to lay eggs each year so, if you have a large population, it may take a few years to get it under control through treatment.

It is often best to try natural treatments before moving up to pesticides that may introduce toxins into the groundwater or affect the health of your family, your pets, bees, or other local wildlife. So, let’s look at some home remedies for grubs and natural ways to get rid of grubs.

1. Encourage birds to hang out in your yard.

Birds love to dine on grubs, so if you do not mind birds digging around in your flowerbeds or lawn, invite more of them to hang out in your yard. You can attract birds with bird feeders, bird baths and bird houses. To learn more about attracting birds to your yard, read Learn the Secrets of Attracting Birds to Your Backyard.

If you dig up grubs, you can also scatter them on top of the ground to encourage birds to eat them. Just know that any that are not snatched up by hungry birds will burrow back into the soil.

2. Feed your chickens.

If you have backyard chickens, you have a ready-made, natural grub treatment that can be quite effective. Turn your chickens loose in your yard, and they will be more than happy to dig up grubs and eat them all day. Keep in mind that the process of digging for grubs is great for soil that needs to be worked but can destroy a flowerbed if left unchecked.

You can also dig up the grubs yourself and toss them in your coop to give your chickens a treat.

3. Limit irrigation.

White grubs require moisture to thrive, so one easy way to shrink the population is to avoid providing them with that moisture. This is not always possible, since they can be found in vegetable gardens and flowerbeds where we want to maintain their visual appeal or in lawns that require more water during the critical summer-fall period where grub treatments are most effective. However, if you have a grass lawn that can go dormant in the summer and recover once water is re-introduced, you could take this opportunity to kill some grubs while also conserving water and lowering your summer water bills.

4. Relocate them.

Grub relocation can be tricky, but if you have a spot in your yard where you do not mind them eating the roots of weeds or other plants, you can dig up your grubs and relocate them away from your lawn.

5. Treat with milky spore.

Milky spore is a bacterial disease that primarily affects white grubs that will become Japanese beetles. Japanese beetles are among the most common culprits when grub populations are found in Southern California lawns and gardens; however, it is difficult to identify which type of grubs you have, and milky spore is only going to help if yours happen to be Japanese beetles.

Even if you are not sure which type of grubs have invaded your lawn, you may want to use milky spore as a preventive treatment that will help if any Japanese beetles show up. You usually need to apply this treatment a couple of times a year for two to three years, but once you go through this process, it can continue to act as a biological control for grubs for 10 to 15 years.

Milky spore is an eco-friendly, natural, non-toxic option, which makes it a great place to start. If you choose to use milky spore, simply follow the instructions on the package. You may also want to purchase an inexpensive Milky Spore Lawn & Garden Dispenser to make it even easier to apply this powder to your lawn or garden beds.

6. Introduce beneficial nematodes.

Nematodes are tiny, parasitic worms that can eradicate all sorts of garden pests, including grubs. They are often used in conjunction with milky spore and offer an organic, safe way to get rid of grubs that will not harm your family or pets.

Because nematodes are living creatures, it is important to purchase them from a reputable retailer and to ensure that you are purchasing containers that are marked with a future expiration date. They are microscopic, so you cannot rely on your ability to see if they are alive once they arrive.

You will want to apply them to your lawn or garden soon after their arrival (or soon after you get them home, if purchasing locally). You will also want to avoid allowing the worms to be in direct sunlight, since even a short time in direct sunlight can render them sterile. To distribute them in your yard, you simply follow the directions on the package to mix the worms with water, and then use a watering can or Nematode Hose End Sprayer to distribute them over your grass or in your garden beds.

You will likely need to introduce a new batch of nematodes into the soil once or twice each year for a few years to establish the population.

7. Apply neem oil.

If eco-friendly, organic gardening is your thing, you probably already have neem oil in your garden shed. This natural pest repellent works wonders on keeping all sorts of garden pests at bay. If you spray neem oil on your lawn at night during egg-laying season, it can keep beetles from laying eggs in your soil, which makes this a great preventive measure. Azadirachtin, which is made from neem seeds, is also used as a natural grub killer, which can be sprayed on your lawn to both repel beetles and kill grubs.

8. Repel the beetles.

There are several natural pest repellents – like the above-mentioned neem oil – that can be used as a preventive treatment. Treating your lawn or garden with one of these repellents assists in keeping beetles away from your yard so that they will not lay eggs that will soon hatch into larvae.

If you are interested in making a homemade grub killer or repellent, you may already have most of the ingredients in your pantry. For example, one popular homemade grub treatment mixes dish soap, lemon juice, and mouthwash with water in a spray bottle that you can then spray on your lawn to repel beetles. Other options include mixing garlic and water or chili peppers and water to create a pest repellent spray.

While this trick can help keep beetles from laying eggs in your soil, it requires you to know when to spray it for maximum effect. Since beetles typically lay their eggs during the summer but it can vary depending on location and weather, you may find yourself treating your lawn repeatedly in hopes of holding the beetles at bay.

9. Make a homemade grub killer with borax.

Before you consider making a homemade grub killer using borax, it is important to note that borax contains boron, and too much boron will kill your grass. If you use a borax grub killer repeatedly on your lawn or in flowerbeds or garden beds, the boron will accumulate in the soil and nothing will grow. So, this option should be used sparingly, if at all.

If you choose to use borax, the simplest recipe is to add one tablespoon of borax with warm water in a spray bottle. Then, use the spray bottle to distribute the borax-water solution on areas where you have found grubs. You will need to repeat this treatment until you have eradicated the grub population, so remember the part about boron accumulating in the soil over time before you choose this option.

Other recipes for borax grub killers include mixing onion, peppers or garlic in the warm water with the borax.

10. Dethatch your lawn.

Leaving a good layer of thatch can be beneficial to your lawn in other ways, but if you are having pest issues and want to get rid of grubs naturally, dethatching is an important part of the process. A thick layer of thatch provides a welcome environment for laying eggs and offers shelter to grubs, so removing it will make your lawn a less-welcoming environment for beetles and grubs.

A thick layer of thatch will also prevent treatments from effectively penetrating the soil, so it is best to dethatch your lawn prior to applying milky spore, nematodes, or other natural solutions, as well as harsher pesticides.

11. Aerate your lawn.

Grubs live in the top few inches of soil in late summer and fall and return to the top few inches of soil to enter the pupal stage in spring. This means that aerating your lawn during these times can injure or kill grubs living near the surface of the soil.

12. Replace your lawn with artificial grass.

Artificial grass is not a natural product, but it is worth adding to this list because it is an effective option that requires no toxic pesticides or repeated treatments. Replacing your natural grass lawn with synthetic turf is a sure way to keep a grub population from taking hold in your lawn and destroying it. Plus, you can enjoy a lush, green lawn throughout the year that looks, feels and functions like natural grass without grub problems or the mowing, watering, weeding, aerating, edging, fertilizing and other tasks that are required to maintain a healthy, natural lawn.

How to Get Rid of Grubs in Your Lawn or Garden: Additional Resources

If getting rid of grubs naturally is not working or you simply want to start with stronger pesticides, it is important to understand the potential effects on groundwater, bees, other wildlife, your pets and your family.

To better understand how the use of grub control products can affect bees and other pollinators, we recommend reading Grub Control in Lawns: Neonicotinoids and Bees published by the Center for Agriculture, Food and the Environment at University of Massachusetts at Amherst.

For best practices in effectively using pesticides that target grubs, we recommend reading How to Choose and When to Apply Grub Control Products to Your Lawn published by Michigan State University Extension. This article also includes a section on protecting bees and other pollinators when using potentially harmful pesticides.

When to Apply Milky Spore

Japanese beetles can completely devour everything in your lawn and garden — trees, shrubs, fruit, vegetables and flowers. Most Japanese beetle treatments on the market will eliminate these garden pests in the short run. However these treatments must be repeated frequently and the beetles will keep returning year after year. Milky spore is considered to be a long-term solution to Japanese beetle infestations.

What Is Milky Spore?

Since the 1940s, milky spore has been manufactured to specifically eliminate the Japanese beetle grub. Milky spore is a naturally occurring bacteria that is reproduced by St. Gabriel Labratories (See References). The active ingredient in milky spore is bacillus popilliae. The spores are activated in warm, moist soil.

The USDA has approved milky spore for use on the beetle grubs. It states that milky spore is not considered harmful to humans, birds, dogs, and other animals. This all-natural, organic treatment will not destroy insects that are beneficial to your garden or negatively impact the water supply including wells, ponds and rivers.

Targeting Grubs

Once the mature beetles emerge from the ground they begin damaging plant foliage above ground. What cannot be seen is the damage beetle grubs do to the roots below the surface. The grubs can be just as harmful, if not more so, as the adult beetles.

Japanese beetle are most vulnerable when they are grubs. By eliminating the grubs, fewer adult beetles will emerge and fewer eggs will be introduced into your lawn and garden, lowering the number of beetles the following season.

To be more effective, after treating with milky spore, you can continue to use other treatments to eliminate adult beetles. See product information in the Resource section below.

How Milky Spore Works

After the application of milky spore, the Japanese beetle grubs begin feeding on the spores. The spores infect the grub, giving them milky spore disease. The disease does not allow a beetle grub to develop into an adult Japanese beetle. Once they feed on the spores, the beetle grubs will die in seven to 21 days.

As the grubs decompose in the soil more milky spore is released into the ground. This cycle repeats until all grubs in the treated area have been eliminated.

When and How to Apply

Milky spore can be applied anytime during the year, except when the ground is frozen. Fall is considered to be the best time to apply the treatment, as the grubs are close to the surface of the warm soil, feeding on roots.

This product only needs to be applied one time and does not need to be retreated on a yearly basis. It is recommended that any treated areas be lightly watered 24 hours after application. Milky spore takes two to four years to thoroughly penetrate an area. As more grubs ingest the milky spore, more spores are naturally released into the soil. The spores should remain in your soil for up to 20 years.

To purchase enough milky spore to treat your entire lawn, plan on approximately one pound for every 4,000 square feet of property. One teaspoon of milky spore should be placed on your grass four feet apart in rows. Each row should then be spaced four feet apart.

by Paul Sachs

Both milky spore disease and beneficial nematodes help control grubs in lawn and garden. Depending on the species of grub, you may want to use both.

Scarab grubs, the broad group of white grubs that feed on grass roots, are difficult to differentiate. The only sure way to identify one positively is to look at the raster pattern on its rear end. Illustrations of these raster patterns can be found in books and articles about insect pests, but a good, quick source great illustrations can be found at

Identifying the Enemy

Japanese beetle raster pattern.

If the grubs infesting your lawn or garden are identified as Japanese beetle larvae, then milky spore is probably the better choice because its effects can last fifteen years or longer. But, in colder climates, it may take two to four years for the active organism, Bacillus popilliae (Bp), to completely inoculate the area treated. If the infestation is large enough (>10 grubs per square foot), you can use beneficial nematodes and milky spore powder at the same time. The nematodes will give more immediate control while milky spore inoculation is spreading.

Masked chafer raster pattern.

If the grubs in your lawn are identified as chafers or any species other than Japanese beetle larvae, Bp probably won’t be effective. There are species of Bacillus bacteria that cause milky disease in other scarab larvae, but they are not currently available. Nematodes may be the only natural option available to you.

Using Nematodes

If nematodes are applied once or twice per year, there is evidence that their populations begin to sustain themselves after two to three years. There is no data available, however, that suggests how long they will last. If nematodes are applied only once and hot dry conditions persist after application, they may have to be re-applied at some point.

The species of nematode applied is also an important consideration. Steinernema spp., for example, are typically an ambushing strain and dwell closer to the soil’s surface than Heterorhabditis spp. Heterorhabditis spp. are typically hunters that can track grubs by following trails of exudates. These nematodes can be found much deeper in the soil than Steinernema and may be more appropriate for controlling scarab larvae. When larvae are infected with Heterorhabditis, they usually turn shades of red.

Nematodes multiply inside the grub host from one or two to hundreds of thousands in just a few weeks. If, however, they are exposed to direct sunlight for more than a few minutes during the application phase, the UV light will sterilize them. They can still infect and kill larvae but cannot multiply. The Steinernema spp. are sexual and at least two need to enter a larvae to multiply. Heterorhabditis are asexual and one can multiply by itself.

The Importance of Timing

Another grub control strategy that may work is to repel adult beetles before they lay eggs. Products containing garlic, pepper, or other repelling extracts can persuade adult beetles to oviposition elsewhere. For this strategy to work, the repellent must be applied before the beetles arrive, which requires some knowledge of the pest’s life cycle. Timing is crucial.

In fact, timing is important regardless of the control you choose. Nematodes should be applied early morning or early evening to avoid direct sunlight. Applying them on a cloudy day is fine and during rain is ideal. They don’t usually need to be watered in but should not be introduced to a dry soil. Nematodes move through soil moisture and can migrate easily into a moist soil. Applying after rain or irrigation is best.

Timing with milky spore is not as important. The spore is a dormant organism, and it only becomes active after a warm Japanese beetle larva has ingested it (larvae are cold blooded and may not activate a Bp spore if ingested by a grub that’s not warm enough). If milky spore powder is applied to frozen ground, it may wash away during heavy rainfall. Milky spore powder is typically applied in a matrix pattern, a teaspoonful every four feet in rows four feet apart. Some newer formulations allow for application through a drop spreader. It is much easier to apply but must be applied three times a year for two years as opposed to just once. Milky spore cannot be effective if there are too few grubs to spread the disease. The greater the number of grubs, the faster the disease will spread. When determining the timing of any control, be aware that evidence of moles is not necessarily a sign of grubs. Moles eat earthworms as well as grubs, and sometimes their tunnels result from mating activities rather than grazing.

All grub controls are more effective at the earlier grub instar stages. Beetles that lay eggs in summer produce young, smaller larvae in late summer/early fall. That’s the best time to apply nematodes. The larger larvae are usually evident in spring and summer and they are harder to control.

About the Author

Paul Sachs is founder and managing member of North Country Organics, a Bradford, VT- based Manufacturer and supplier of natural land care products. He has studied natural soil system dynamics for close to 30 years and is considered one of the foremost authorities in the country on organic land care. He has written five books, hundreds of articles for trade journals, and speaks regularly at association conferences for professionals involved in both agriculture and horticulture. He has served as a member of the Technical Advisory Panel for the National Organics Standards Board of the USDA and is currently a board member of OMRI (the Organic Materials Review Institute). You may reach Paul through his website:

Japanese beetle grubs and timing of milky spore application

There are a few things to consider about applying milky spore. One consideration is that studies show it has limited effectiveness. A publication by CSU that was just released puts the effectiveness at less than 5% reduction in grub populations. That same publication had information on other types of controls that are more effective. Here is a link to this information.

If you want to try the milky spore, apply it when larvae are active. You would apply it when they are actively feeding on turf grass roots which is May-Jun and Aug-Sept.

Another thing to consider is whether you have evidence of grubs in your lawn. If you had adult beetles in your garden last summer, it doesn’t necessarily mean they originated from your lawn. The adults can travel up to five miles. If you had grub damage in your lawn you would notice your lawn looking drought stressed, even when you were adequately watering and you would be able to pull up clumps of grass easily because the roots would be damaged. The damage would have been most noticeable in Aug-Sept.

The link above will give you some good information about how to manage Japanese Beetles at all stages of their life cycle.

Hope this is helpful and we empathize.

What Is Milky Spore: Using Milky Spore For Lawns And Gardens

Japanese beetles can strip the foliage from your prized plants in no time. To add insult to injury, their larvae feed on grass roots, leaving ugly, brown dead spots in the lawn. The adult beetles are tough and difficult to kill, but their larvae are susceptible to several biological controls, including milky spore disease. Let’s learn more about using milky spore for lawns and gardens to control these grubs.

What is Milky Spore?

Long before horticulturalists coined the terms “integrated pest management” and “biological controls,” the bacterium Paenibacillus papillae, commonly called milky spore, was commercially available to control Japanese beetle larvae, or grub worms. Although it isn’t new, it is still considered one of the best methods of control for Japanese beetles. After the larvae eat the bacteria, their body fluids turn milky and they die, releasing more of the bacterial spores into the soil.

Japanese beetle larvae are the only organisms known to be susceptible to the disease, and as long as they are present in the soil, the bacterium increases in numbers. The bacteria remain in the soil for two to ten years. When using milky spore for lawns, it can take three years to achieve control of the insect in warm climates, and even longer in cooler areas. You can also use milky spore in vegetable gardens without fear of crop damage or contamination.

Ideal soil temperatures for using milky spore are between 60 and 70 F. (15-21 C.). The best time of year to use the product is fall, when the grubs are feeding aggressively. Although the grubs are in the soil year round, it only works when they are actively feeding.

How to Apply Milky Spore

Knowing how to apply milky spore is important for effective control. Place a teaspoon of milky spore powder on the lawn, spacing the applications about four feet apart to form a grid. Don’t spread or spray the powder. Water it in with a gentle spray from a hose for about 15 minutes. Once the powder is watered in, you can safely mow or walk on the lawn. One application is all it takes.

Milky spore won’t completely eliminate Japanese beetle grubs from your lawn, but it will keep their numbers below the damage threshold, which is about 10 to 12 grubs per square foot. Although Japanese beetles can fly in from your neighbor’s lawn, they will be few in number. Japanese beetles only feed for two weeks, and visiting beetles will be unable to reproduce in your lawn.

Is Milky Spore Safe?

Milky spore disease is specific for Japanese beetles and it won’t harm humans, other animals or plants. It is safe to use on lawn and ornamental plants as well as vegetable gardens. There is no risk of contamination due to runoff into bodies of water, and you can use it near wells.

Milky Spore Disease

Q. OK, you have convinced me to wait until the fall to plant new grass seed. But how about the grass I have now? Is it too late to put down Milky Spore? When is the best time to assure it will ‘take’ in the soil for the long term? Thanks,
—Jaan in Yardley PA

Our lawn was so infested with grubs that we dug the whole thing up and are having new sod put in. Is there something I should put in the soil to kill any remaining grubs before the sod is laid? Thank you,
—Joan in Ottawa, Ontario; CANADA

Mike: I have neighbors who are going to apply milky spore on their lawn to kill grubs; they say applying it three times a year will rid my yard of grubs after three years. But I couldn’t find it for sale at the Gardens Alive website, so I’m thinking it might not be that good. What IS the story with this stuff?
—-Tony in McLean, Virginia

A. Tony: I don’t work for Gardens Alive; they simply host my Question of the Week. But I did ask the folks at GA—who seem to carry just about every other natural pest control—why they don’t carry milky spore. They explained that they had heard great things about its ability to control the grubs of Japanese beetles in turf grass, but had also heard about recent tests indicating it may only work in the lab. A little checking around revealed that there’s quite a bit of disagreement about this stuff in the research world.

So I called THE authority on Japanese beetles and their grubs, Dr.Michael Klein, Adjunct Professor of Entomology at Ohio State University and former Lead Scientist for what was known for many years as the USDA”Japanese beetle lab” and is now called the “Horticultural Insects Unit”. Dr. Klein explained that when Japanese beetles entered the county (on a shipment of plants to Riverton, New Jersey sometime prior to their discovery in 1916) they were rare in their native country, and considered good luck because of their beautiful green and gold’finery’.

Their famed natural enemy was discovered—also in New Jersey—in the1930s. Although many of us call this stuff “Milky Spore”, Dr. Klein explains that that’s actually a brand name; the correct generic term,he says is “milky disease”. Anyway, it appears that this naturally occurring soil organism was already in the Jersey dirt, rather than coming over with the beetles. (Until very recently, nobody had even found it in Japanese soils.)

The name isn’t the only thing we’ve been getting wrong, says Dr. Klein;a lot of misinformation has been whispering down the lane here…

Misconception #1: “Milky spore(disease) ONLY works on JAPANESE beetle grubs.
Dr. Klein explains that although it does work best against Japanese beetle babies, some strains have been shown to infect other whitegrubs—which is good, because other beetle grubs are learning how much fun it is to live in turf.

Misconception #2: “The disease just has to be in the soil to work.”
Dr. Klein explains that very specific conditions must exist for the disease to do its job: To become infected, a grub has to be actively feeding in warm soil and ingest some spores. Just being in the same dirt as the disease doesn’t harm grubs, and if the soil is cooler than65 degrees, the spores just pass right thru without harm.

Although the distinctive crescent shaped grubs we find in lawns and gardens already look pretty milky, grubs that are infected with the disease look even milkier, he explains. If you want to be sure, clip off a leg; the fluid will run clear from a healthy grub and milky white from an infected one. Sounds like you’re checking to see if a turkey is done.

Anyway, although the number of variables involved makes it somewhere between hugely difficult and totally impossible to prove conclusively,Dr. Klein feels that milky disease DOES work naturally in many areas,and should be able to be introduced successfully in areas that meet the necessary requirements of soil temperature and grubs.

And at least one piece of information people have been dispensing about milky disease IS correct—it lasts as long as its reputation.Researchers have found the disease—which affects no other creatures besides grubs—still active in soils that were treated decades ago.

The more grubs in the soil when you apply it the better, as infected grubs breed more of the disease. The best time to infect large numbers is in early Fall, when the grubs are in nice warm dirt, chewing grassroots madly to put on fat for the wintertime. So applying a concentrated form of the disease (isolated from actual grubs and available in bags and shaker cans at most garden centers) anytime over the summer would seem best. Just don’t use any other grub-killers,warns Dr. Klein, or the milky disease spores won’t have anything to infect.

Repeated applications shouldn’t be necessary if there are a good number of grubs in the soil to become infected. Three times total seems excessive, much less three times a year. As you’ve always heard, it takes several years to build up enough disease spores in your soil to make a noticeable difference—around three in the Philly-DC area; five up in New England and Canada.

Don’t worry about existing grubs in the Spring. Any nibbling they may do after rising to the surface in preparation for their final metamorphosis into the flying defoliators we know so well is pretty inconsequential, AND the Northern grasses that house the vast majority of beetle grubs (at least so far) are growing at a rapid pace in the Spring. The real damage is done to these cool-season turfs in the Fall,when the grass (which thrives in cool weather but can barely tolerate a really hot and dry July and August) is weak from summer heat stress and the grubs are truly voracious.

If you want to eliminate grubs now in the hope of reducing adult beetle damage this summer, two of Dr. Klein’s favorite non-chemical treatments are beneficial nematodes and the legendary Spikes of Death. We’ll detail those options and talk about the different adult forms and the damage they cause in Part Two of this Special Report next week.

You Bet Your Garden Question of the Week ©2006 Mike McGrath

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Three Reasons You Should Not Be Using Milky Spore

April 10, 2012 | By Mr Grass,
Updated June 24, 2019

According to a University of New Hampshire publication on milky spore disease, there are more reasons NOT to use this product than to use it in your home lawn. Milky spore has been around for decades and was the first biological disease to control Japanese beetle grubs. Milky spore comes in a powder and consists of a bacteria.

The first reason not to use milky spore is that it was manufactured to control ONLY Japanese beetle grubs. Unfortunately there are many more turf damaging grubs in NH and VT including Asiatic beetles, European and masked chafers, June and May beetles and armyworms. So now you understand that even if milky spore could work, you would only be controlling one grub out of many…not good odds.

Secondly, you must have sufficient numbers of Japanese beetle grubs in your lawn to promote the bacterial population enough to expand and spread out in the soil. Therefore, if you do not have a large Japanese beetle grub population, one where you would likely see damage – why bother?

The third reason not to use milky spore in NH and VT is the fact that the soil temperature must be 60-70 for three months. This consistently high soil temperature rarely occurs in our region. Additionally, the bacteria can take over 4-5 years to build up…under ideal conditions…with a high population of Japanese beetles grubs! Wow!
To summarize, even under ideal conditions, using milky spore disease to control grubs, even Japanese beetle grubs, is a serious waste of money and time. It’s best to consult with a lawn care professional because without knowing insect or disease life cycles, product components, mode of action, and application method – you could be applying the wrong product, at the wrong time, for the wrong pest.

Organic Lawn Pest Control: Milky Spores and Nematodes

Milky Spores and beneficial nematodes are the two most widely recommended pest control solutions for organic lawn care maintenance. Insect and grub infestations are perhaps one of the biggest challenges for maintainers of organic lawns. The temptation to simply revert to the use of commercial chemicals and pesticides is great, but with simple applications of Milky Spores and nematodes, insects and grubs can be thwarted, maintaining the health and beauty of your organic lawn and those living and playing on and around it.
As often happens with lawns and gardens, a heavy infestation of one or more type of damaging insect or grub often indicates an imbalance in your lawn’s ecosystem. Many times, an imbalance is the direct result of the use of wide spectrum pesticides and chemicals meant to solve the problem at hand. Harsh chemicals and pesticides can kill more than just target insects. Birds and other beneficial, predatory insects that feed on lawn parasites are often killed as well, and in the absence of natural enemies, grubs and parasites may thrive as insect populations reproduce more quickly. To remedy the situation in your organic lawn, you need to reintroduce predators and restore the natural balance so that the one species does not take over without restraint.
Nematodes, commonly referred to as ‘beneficial nematodes’ or ‘predatory nematodes,’ are microscopic worms. Beneficial nematodes control insect and grub populations by infecting the host, usually a grub or insect larvae. Nematodes carry bacteria that break down the internal structure of the host (grub or larvae) through enzymes. Death of the host occurs within 24 to 48 hours. Beneficial nematodes enter through the skin or an orifice on the larvae, mature, and lay their eggs. Once nematode eggs hatch, the young nematode larvae feed on the broken down interior of the insect larvae. Beneficial nematodes go through four stages of growth and exit the host body during their third stage of maturation to begin the cycle again.
Predatory nematodes infect a very wide variety of lawn parasites (over 200 larval insect species) and will kill most of the larval insects invading an organic lawn. As beneficial insect larvae are usually faster moving and more active, they are seldom the victims of nematodes. Earthworms are not parasitized by nematodes. Predatory nematodes occur naturally and are not considered a threat to humans and pets as there is no evidence that they can survive and develop inside such a host.
Predatory, or beneficial nematodes are most successful when applied to a moist, recently irrigated organic lawn with soil temperatures between 55 and 99 degrees Fahrenheit. Apply nematodes when grubs or larvae are present. It is also a good idea to pay attention to what pests are plaguing the rest of your organic yard and gardens. Remember that most insect invaders start with grub and larval forms in the ground. If pests have plagued your plants and trees as well, look to the ground. Destructive insects and beetles, such as the highly destructive Japanese beetle, begin as lawn grubs. An application of nematodes can assist in all around organic pest control. Among the many species beneficial nematodes feed on are fleas, gnats, weevils, cutworms, and several species of wood borers.

Beneficial, predatory nematodes are a good ‘quick fix’ for the organic lawn as they begin to kill grubs and larvae within 24 hours of being ingested. Nematodes are a good line of defense also because of the large number of hosts they infect and kill. However, as nematodes are somewhat sensitive to temperature and periods of drought, a second line of defense may be called for to provide long term, lasting grub control. Treatment with a Milky Spore application can be used alone as a defense against White Grubs (Japanese Beetle Larvae), or in partnership with a solution of beneficial nematodes.
Milky Spores
Milky Spore applications work in much the same manner as an infection by nematodes. Milky Spore is a natural bacteria that infects the grubs of Japanese Beetles with Milky Spore Disease. The disease paralyzes and kills the host grub. When the dead grub breaks down, it releases billions of new spores into the soil, which in turn infect and kill other grubs. An infected grub will die within one to three weeks of being infected by Milky Spores.
For the best results, Milky Spores should be applied when white grubs are feeding. Grubs feed during the Spring and Fall. Grubs feed more heavily in the Fall as they are building fat stores and preparing for Winter dormancy. Milky Spore applications begin working immediately if applied while grubs are feeding. Grubs take in the spores when they feed on grass roots. Optimal levels of control occur after one to three years of spore application (the lower timeframe applicable to warmer climates).
Weather is of little concern to Milky Spores, another advantage it has over nematode applications. Milky Spore is not affected by Winter or freezing, and once established, Milky Spore treatments have been proven effective for 15 years or more. Rain is of no consequence to applications of Milky Spore, so long as a heavy rain immediately after application does not wash the applied spore dust away. A light to moderate watering is helpful to help Milky Spores penetrate the soil to where grubs will ingest them. Avoid raking or mowing your yard until the spore has had a chance to soak into your organic lawn.
Like beneficial nematodes, Milky Spores occur naturally and so are not toxic to humans and animals. Pesticides and chemicals do not effect Milky Spores, so they can be applied even if you have previously treated your lawn with chemical pesticides and fertilizers. Milky Spore is harmless to vegetables, flower gardens, and water supplies. Birds and other wildlife are immune to the effects of Milky Spore as well. Your organic lawn and gardens will benefit from having more healthy birds around to feed on parasitic insects once you have restored the balance to your lawn’s ecosystem by doing no harm to species eating pesticide poisoned grubs and insects.
As an added benefit, you may notice a decline in the activity of small animals that feed on grubs, like moles and skunks. Minus the food source in your lawn, these menacing animals will search for food elsewhere. (Perhaps you will want to share your treatment solutions with your neighbors.)
Both beneficial nematodes and Milky Spores are good courses of treatment for infestations of grubs and pests in your organic lawn. Harmless to nearly everything but the parasites you wish to target, nematodes and Milky Spores are the most widely recommended defenses against organic lawn invaders, eliminating the harm wide spectrum pesticides inflict and restoring balance to the world of your organic lawn and garden.

By George Weigel/The Patriot-News

Q: I discovered yesterday that I have a moderate amount of grub damage to my suburban Harrisburg lawn. My questions concern the usage of chemical control for the grubs. I plan on applying milky spore to my lawn for future control but what about now? Although I hate using chemicals because of the environment, unless I apply chemicals now, what will stop the grubs from killing my lawn next year? If I do use one of the products you mentioned, do I apply it to the entire lawn and do I do that before I seed the barren areas?

A: You’ve got two main options. One is the chemical approach. For quick kill now, Dylox (trichlorfon) is considered most effective with Sevin (carbaryl) as second. Then for preventing grub outbreaks in future years, apply either Merit (imidacloprid) or Mach2 (halofenozide) anytime from late May through June.

Approach 2 is using a targeted and lower-impact game plan. That means milky spore bacterial disease for a long-term control. Unfortunately, milky spore doesn’t make much of an immediate impact. It takes a few years to build up to its maximum protection.

The only non-chemical short-term control I know of (other than a hammer) is a type of microorganism called nematodes that can be spread in the lawn this time of year. They’ll make a dent in the population, but probably not as effectively as the chemical insecticides above. Grub-controlling nematodes also are hard to find. If you can’t find them at your favorite garden center, one online source is Gardens Alive ( Look for the product called Grub-Away Nematodes. These should be applied each spring and fall for best control. If you go that route, you may not need milky spore.

If you prefer milky spore, I’d suggest just surrendering to this year’s grubs and focusing on future problems by getting your first milky spore treatment down ASAP. Don’t apply a chemical if you choose milky spore because this disease needs grubs to become infected and manufacture even more disease bacterium when the grubs die and spew the disease into the ground. In other words, if you kill off the grubs with a chemical, you’ve wiped out the little “disease-brewing factories” that milky spore needs to get going.

Just reseed the areas that the grubs kill. You may need to reseed a bit more next spring when the grubs resume feeding, but as the milky spore takes hold, your trouble should go downhill.

Milky spore can be applied anytime the ground isn’t frozen. It comes in powder form that’s typically applied just once or twice, and in granular form, which is to be applied both spring and fall for two to three years. Once in the ground, milky spore is reasonably effective against Japanese beetle grubs for 10 to 20 years.

No matter what product you use, you can reseed dead areas. None of them will affect the grass germination.

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