In this article you’ll learn whether the scientists recommend using chemical or natural treatments for grubs, which ways are more effective and can protect your lot for over 15 years, and which of the 10 best grub killers will solve your problem.
Farmers face the issue of grub worms on their lots from the end of the summer till the beginning of the fall. The worms feed on plant roots causing the lawn to wither and bronze, and the soil becomes loose. You will find out what the six most effective treatment ways approved by the scientists for short and long term. You will decide whether it is better to use chemical or natural killers. Finally, check out our list of the TOP best grub killers.
Finding the perpetrator is a piece of cake, just check the damaged area for these pests. You will hardly confuse them with anything else, as grub worms have a peculiar C-shape body, six short legs, brown head and a cream body color. Their lower abdomen is darker due to the soil particles in it. Grub worms can reach two inches in length.
Remove some of the damaged soil carefully, (especially in places where green grass borders brown grass) and check for the grub worms matching the above description. If you find five or fewer, do not worry, but they can definitely do harm to your lawn if there are over ten of them. Still, consider other factors of grass withering. For instance, in shady places, grass roots weaken and tear easily and larvae do not hatch. Another signal of these pests infecting your garden will be skunks and raccoons digging the lawn at night in search of food. It is highly likely that they are looking specifically for these pests.
Although lawn grubs lay eggs randomly, they have certain preferences. As a rule, they tend to lay eggs on sunny, moist lawns, so if the weather is dry and you have a well irrigated lawn, your chances of attracting lawn grubs are very high. On the other hand, if the summer has been rainy and it is not only your lawn, but also your neighbors’ lawns that have received enough moisture; there won’t be many grub worms. The thing is that they prefer to lay eggs as far as possible from each other, so if several lawns have equally attractive conditions, they won’t concentrate their offspring in one place.
Adult grubs lay eggs in the soil during the summer. Once the grubs hatch, they feed on plant roots and descend deep into the soil once it becomes colder, to spend the winter there. In the spring, grub worms return to the surface and keep feeding on the roots until they become ripe. The biggest damage is caused from mid-September to November or from March till the beginning of May.
Once you’ve diagnosed the problem, decide which treatment approach is suitable for you: a curative or preventive one. In both cases, the chemicals make plants toxic for pests. The former is appropriate for getting rid of existing grubs while the latter one is aimed at removing them in prospect. If the upper soil layer seems to be uninfected, there is no need to use an insecticide, even if there are several grub worms.
A curative approach is suitable for solving the problem quickly, i.e. if you have discovered grub worms on your lot and would like to immediately get rid of them. It is suitable for the summer when the larvae are small and actively feeding near the soil surface. This method won’t be equally effective in the spring when grub worms grown and become quite large. As soon as the insects reach their maximum size (usually by mid-September), a curative approach will hardly result in removing more than 50% of grub worms on the lot.
This approach implies using Sevin and Dylox that contain carbaryl, clothianidin and trichlorfon. The latter chemical has certain restrictions as trichlorfon is banned for use on school territories of certain states, mainly because this substance is extremely soluble in water. Carbaryl has been known in the USA since 1959 and acts by destroying the insects’ nervous systems, thus causing death. It is toxic for humans and causes such symptoms as headache, excessive sweating, muscle weakness as well as nausea, tears and other symptoms for animals. The substance is dangerous if swallowed, inhaled and it can be dangerous if it touches your skin. According to the University of Kentucky College of Agriculture, Food and Environment experts, carbaryl is less effective than trichlorfon.
The University of Massachusetts Amherst says, “Management of grubs in the soil is possible with insecticides, and predatory nematodes may also have some value. Chemical control of adult beetles can prevent extensive leaf damage, but is not guaranteed to prevent egg laying. Traps with combination pheromone and floral scent lures are commercially available for Japanese beetle, but their placement near strawberries may actually attract more beetles to the area.”
“To avoid the risk of white grub problems, do not plant on newly turned sod land. Rather, plow the field, let it lie fallow or in a rotational cover crop such as Sudan, buckwheat, or a salable crop such as pumpkins or squash for at least one season prior to planting with strawberries. Also, avoid siting a strawberry field next to large grassy fields which would be a source of these beetles. Control grassy weeds within the planting, which are especially attractive to egg-laying Japanese beetles and European chafers.”
A preventive approach is considered to be most effective and should be taken before larvae hatch, i.e. in the middle of the summer. However, it solves future problems and does not act against existing pests. Once you apply a preventive insecticide, you will provide your garden with great protection against future generations of grub worms. How do you know that your soil requires treatment? The golden rule is the following: if you discovered these pests last fall or spring, do not hesitate to use a preventive insecticide for a year or two.
Merit, MachII and GrubX that contain such chemicals as imidacloprid, thiamethoxam, halofenozide, clothianidin or chlorantraniloprole are considered preventive control products. They are effective against grub worms that hatched in July and not against ones that are found from September till May. As a result of using these products, the number of pests on your lot will drop by 75-100%.
The Michigan State University Extension experts additionally distinguish another active ingredient of insecticides, chlorantraniliprole. It is also considered to be preventive, but can be applied at any time as soon as green grass begins growing. However, research has shown that the effect is maximized if chlorantraniliprole is used from April till June. In this case, the chemical will consistently eliminate 65% of pests. Chlorantraniliprole is an ingredient of Acelepryn (for commercial use) and GrubEx (for homeowners). This is a relatively new low-toxic insecticide. The toxicity is so minor that there is no “Caution” label.
The Michigan State University Extension scientists estimate that products that contain only such active ingredients as lambda-cyhalothrin, gamma-cyhalothrin, bifenthrin, deltamethrin, cyfluthrin or permethrin will not solve the problem of grub worms. These ingredients are only effective against the insects that feed on the surface and not against larvae consuming roots.
The products are available as granules that should be used along with a fertilizer spreader as a liquid concentrate or a ready-to-use sprayable mixture. Pick a product and mind your own, your family’s and your pets’ safety. Granules are the safest as the insecticide will be consumed. Ready-to-use liquids pose a moderate threat as liquids can be spread with the wind. Concentrates carry the biggest risk as it is crucial to mix them with water in a proper ratio. In all three cases, you can only walk on the treated territory after the grass dries.
If you are not attracted by synthetic treatments, use natural ones. We’ll share several popular methods with you.
1. Apply milky spore powder, i.e. natural bacteria that infect grubs when they feed on the infested lot. The powder is only effective against Japanese beetle. The product provides stable results regardless of weather conditions. However, the effect depends on the number of grubs on your lot, as the more there are, the faster the deadly grub disease spreads. Moderately irrigate the soil with water. In some cases, the grubs infected during late fall can survive until spring. They won’t develop any more, though, and will eventually die.
2. Use neem oil, a natural insecticide made of the evergreen Indian tree. This organic biodegradable substance does not have any substantial side effects, as the Environmental Protection Agency estimates. Mix neem oil with water and spray damaged grass. The insects consume this insecticide as if it were a natural hormone. Once ingested, neem blocks real hormones and the pests forget how to eat, lay eggs or even fly. Even if they manage to lay some eggs, they won’t hatch. At the same time, neem oil won’t harm useful insects. In addition, it has a repelling effect as its presence and smell scares off the insects that consume leaves. It does not yield quick results, but in the long run, you will end up with a balanced environment.
3. Heterorhabditis bacteriophora nematodes, also known as Hb nematodes in stores, show decent results. These small worms will start looking for grub worms underground, and once they find them, they will secrete bacteria that kill grubs. Apply nematodes on an irrigated soil, and water it once more after setting the nematodes free there. The best time for the procedure is early morning or early evening as at that time, you will avoid direct sunlight. The weather should either be sunny or rainy, but do not let the nematodes into the soil when it is when it is too hot or dry or when it is raining heavily as the rain can simply wash them off.
4. The birds will do you an invaluable favor, but getting them may cost you a fortune. The Garden Design magazine quotes one of the gardeners: “Because we love birds, we just happened to put up 5 houses for house wrens, one in the front yard, one in each side yard, and two in back — strategically placed so they would not see each other’s houses, being so territorial. Since we did this, house wrens have nested every summer in every house. We have no more grubs, squash bugs, or tomato hornworms. It is almost unbelievable…but true. We never use pesticides of any kind and haven’t for 18 years.”
Effectiveness Scale: 1 being the least, 10 being the most effective.
|Curative Chemicals||FAST. Quickly solves the problem, is used in the summer. |
|Carbaryl is very toxic for some helpful insects, and bees. Removes 74-77% of grub worms.|
|Preventive Chemicals||Causes minimum to zero damage, provides long-term results and complete removal of grub worms. The number of pests will drop by 75-100%. |
|You should decide whether to use this treatment when you still don’t know the extent of pest infestation. These chemicals are useless on the pests that have already infected your soil.|
|Milky Spore Powder||Is natural and safe. Kills larvae without harming either the garden nor humans. Unlike nematodes does not depend on the weather (even if there are heavy downpours or frosts). Can be used if the soil has previously undergone pesticide treatment. |
|Is only effective against Japanese beetle larvae, best results are seen only after over a year.|
|Parasitic Nematodes||Are safe and natural, act within 24 hours, kill grub worms but are useless against earthworms and other helpful insects. |
|Reacts to temperature and drought, incompatible with chemical pesticides.|
|Neem Oil||Is safe and natural and will control insects at all development stages, stimulates earthworm activity (which is useful for the soil). Is a good choice for removing a new pest generation. |
|Has a sharp unpleasant odor, the first results are not fast and seen only within two weeks.|
|Birds||A natural method for getting rid of grub worms that shows good results. |
|Bird care requires investment, birds can harm your lot.|
We picked the best grub killers that are effective and approved by the scientists:
GrubEx with the active ingredient chlorantraniliprole is used for preventive soil treatment. The product’s effects lasts for up to four months. It is recommended for use in the spring or early summer as the preventer will avert the damage before the grubs hatch. A single pack will be sufficient to treat an area of 5000 square feet. Fill the sprayer with it and spray dry lawn. After this, moisten the soil in order to activate the chemical.
Among all preventive treatments, the ones containing chlorantraniliprole are the safest. Allegedly, it does not do harm to earthworms and soil bacteria. However, some users disagree with this. One of them commented: “It may damage some but not all of the earthworms. But it’s a whole lot better than your whole lawn getting eaten up.” Scotts GrubEx distribution is restricted as it cannot be used in the state of New York. Half of the users gave this product a five-star rating.
Price: Check the current price
Bayer offers two products against grub worms with different active ingredients: granules and a spray. Let us begin with granules. The manufacturer promises to eliminate grub worms within 24 hours on the same 5000 square feet area for almost the same price. These trichlorfon-containing granules are used during curative treatment. This substance is less safe and its use is partly restricted. Moreover, unlike the previous product that is made in the USA, Bayer Advanced is made in China.
Do not use it in the kitchen-yard and on edible plants. You can apply it on flower beds but avoid the actual leaves and petals. One of the users was satisfied by the use of this product and left the following comment: “The 24-hour Bayer kills grubs and is the best of the grub products that I’ve used. Best time to do this is end of August or early September.” 64% of this website’s users gave this product a five-star rating, although 11% believe it deserves zero stars. According to the description, the same treatment is effective against ants, scorpions, ticks and other insects.
The second item is Bayer Grub Control Spray and its active ingredient is 1.47% imidacloprid (Merit). It promises to kill grub worms for the entire season after a single use. The spray will also cover an area of 5000 square feet but is less popular than granules. The feedback is contradictory, but those users who were able to restore their blossoming lawn without any brown bald spots, recommend using this preventive method twice: in the fall and in the beginning of spring.
Bayer Spray Check the current price
This ready-to-use dust contains 5% carbaryl as an active ingredient. It is also used as curative treatment. The manufacturer claims that the product is suitable for fruit and veggie gardens and for the flower beds with decorative plants. Nevertheless, it is recommended to wear rubber gloves when applying it and to not let children and pets on the treated area until the dust settles down. The users are also cautious about applying Sevin on fruit and vegetables. If you treat lettuce with it, for instance, rinse it thoroughly and do not consume for three days.
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It contains 22.5% of the active ingredient carbaryl and is much more expensive. This concentrate is suitable for large gardens and can kill up to 100 species of insects targeting fruit, vegetables and flowers. It is not for indoor use. Once you dissolve the concentrate in water, you will end up with 86 gallons of ready-to-use treatment, which will be enough to cover over two acres of territory. That is why eventually Sevin Concentrate will be more cost-efficient than the previous goods, especially if you need to treat a large area. This product has also been approved by the users as 77% gave it the maximum rating. However, the users use it with caution as “you have to be very careful because it is a toxic item and you don’t want to get any on your hand,” as one of the users of this concentrate warned.
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100% natural grub killers are more expensive, Milky Spore. This is also a harmless natural product that is recommended as an environmentally friendly grub control item along with the nematodes. Unlike the latter, milky spores can be applied in any weather and any time from spring to fall. Remember, though, that it only acts against Japanese beetles’ grubs.
The treatment covers a 7000 square feet territory and the manufacturers promise that the pests won’t enter your lot for the following 15 years after use! Given such prospects, the high price seems justified.
Scientific research attests to the duration of its effect: “In fact, studies have demonstrated that milky spore can last 15 to 20 years in the soil. It has been thought that milky spore may remain in the soil in a dormant but viable state until new infestations of grubs are present,” as claims Raymond A. Cloyd, University of Illinois Extension.
Several users share their positive experience of using this treatment. One of them commented: “I only did 1 application…& it worked!!! And it didn’t kill my wonderful earthworms! It has been about 5 months and still no grubs.”
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Environmentally friendly Steinernema Feltiae nematodes are compatible with useful soil bacteria and only kill the insects you don’t need. They will not immediately yield results, but within three-four months.
Studies have shown that treatments containing Heterorhabditis bacteriophora nematodes are more effective than the ones with Steinernema glaseri or S. Carpocapsae, although no nematodes showed as steady results as chemical insecticides do. Steinernema are known to inhabit the upper layers of soil closer to the surface and to follow their victims, while Heterorhabditis digs deeper into the ground and hunts actively, chasing its victim. That is why you might as well test another treatment containing Heterorhabditis bacteriophora. If we compare descriptions, we will indeed see substantial differences as Steinernema Feltiae nematodes cover only 200 square feet, and Heterorhabditis bacteriophora are able to cover up to 3000 square feet for the lower price.
However, Nema Globe 4003003 Grub Buster has a competitive edge as its nematodes kill up to 230 insect species, more than the nematodes of the second type do. The users’ ratings also favor the former (55% versus 49%). One satisfied user states: “This is the third year for our 3,000 SF organic garden and all of the crops are healthier than they have been in the past.”
The treatment can be used by letting the nematodes directly into the ground or by spraying them. Once in the soil, the insects will chase and kill grub worms. You should store nematodes in the refrigerator.
Nema Globe 4003003 Grub Buster: Check the current price
Here is yet another natural treatment, available on with a good discount. It is suitable for protecting vegetables, fruit, flowers and shrubs but is not recommended for application on tender, withering or freshly transplanted plants. The concentrate combines three garden products: an insecticide, a fungicide and a miticide which is extremely cost-efficient for such a low price.
Its active ingredient is neem oil and thanks to it, the insects quit feeding, laying eggs and eventually they die. You won’t yield immediate results, so aim for long-term prospects. To guarantee best results, the manufacturer recommends using Garden Safe Neem Oil Extract Concentrate once a week or a fortnight. Apply it early in the morning or late at night.
66% of users gave Garden Safe Neem Oil a five-star rating. Some of them worry that not all ingredients are listed on the label, but the general rule is not to mention harmless components.
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Unlike the previous product, this is not a concentrate, but a spray. It protects vegetables, fruit, flowers and shrubs and kills 45 insect species. It is recommended for hydroponic gardening. Be careful when using it though as it contains not only neem oil and potassium salts of fatty acids, but also pyrethrin, which is a pesticide affecting the insects’ nervous system.
This is a cheaper neem oil-containing treatment, and it is less popular with users, some of them were frankly disappointed as one of the comments reads: “Honestly, it didn’t seem to work on anything. My mother ended up just throwing it away.” Overall, 60% of the customers were satisfied.
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Dr. David Shetlar, the Department of Entomology, Ohio State University
David Shetlar is a professor of urban landscape entomology at Ohio State University. He teaches general entomology and focuses on turfgrass entomology research. Dr. Shetlar has co-authored several books on turfgrass insects and has numerous scientific publications.
“There are many approaches for the management of the white grubs and the first one is tolerance. I know this is easy for me to say but can be very difficult for a lawn care company to explain to their customer when that customer digs in their flowerbed and finds a grub or two. And they wonder, why you do not control my grubs. Just because you found 2 or 3 grubs, that is not enough. You need grubs about 8 to 10 grubs per square foot before you would really achieve damage. To prevent grubs, use residual lifespan of insecticides that we apply to the turf. Even though we know that most white grub populations arrive in July or August, some of these insecticides have residual activities of 3 to 4 months, and so we can apply them earlier to prevent those grub infestations from happening”.
Timely treatment is crucial as otherwise even the most effective product won’t provide proper effect. Mid-August is the most favorable period for undertaking a curative method as the grub worms are still small. By the end of September, the grubs have grown and dig deeper into soil outside of the insecticide action area due to the drop in temperature. Spring is also not the best curative grub control time as after the winter, the grubs are quite large.
In general, it is quite troublesome to find the right time for using curative control. When applied too early, insecticides can decompose in the soil before grub eggs hatch, and if you use them too late, it will be harder to kill grubs that have already damaged the soil. This can be avoided by using a preventive approach that implies a more flexible treatment schedule. The best time for using preventive products is mid-June or mid-July, before the grubs hatch. Preferable season can also vary depending on the region.
Remember to irrigate the soil abundantly after treatment. To determine the necessary amount of water, place several coffee cups on the lawn. Once they are filled for an inch with water, the soil is sufficiently moistened.
Although if used properly, modern insecticides do not pose any serious risks and help prevent grub worm damage, make sure you follow these safety rules.