Some insects are extremely beneficial to your lawn. For example, pollinators help plants reproduce, predators get rid of unwanted pests, and saprophytes help break down organic matter into nutrients in the soil. On the other hand, some insects only damage the grass in your yard. Lawn grubs are a bane for many homeowners who want healthy lawns with lush, green grass.
Grub worms are the larval stage of several different kinds of beetles. They live beneath the surface of the soil, feeding on roots of grass until the grass above withers and dies. Because they live underground and return every year, they can be difficult to kill. However, by using the right method at the right time, you can kill the grubs before they do significant damage, or even prevent them from hatching in the first place.
If you’ve got a lawn grub infestation that’s not responding to DIY pest control methods, consider hiring a professional lawn care and pest control company to treat the grub problem. I recommend TruGreen, a nationwide company with many years in the business of caring for lawns, including removing common pests.
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Preventing Lawn Grubs
If at all possible, you want to prevent a white grub infestation in the first place. Because these pests feed on root systems, it can be difficult to catch an infestation until adult beetles emerge from the soil.
Although none of these methods is foolproof, keeping up with regular lawn maintenance can go a long way toward preventing common problems, including lawn grubs. One way to maintain the landscaping is to mow your lawn regularly. You can also maintain bird feeders, as natural grub predators serve as a reliable grub treatment.
Grow Grub-Resistant Grass
Certain species of grass are more likely to attract grubs than others. Kentucky bluegrass is an extremely popular cool-season grass, but it’s a favorite meal for beetle grubs. Consider switching to a hardier species like tall fescue.
Eliminate Adult Beetles
Keep an eye out for beetles during the spring and summer. Japanese beetles will fly around during the day, and masked chafer beetles will come out at sundown. If you start seeing adult insects, it’s a fairly certain sign that they’re laying eggs in your yard. Use a pesticide designed to remove beetles, such as one that contains pyrethroid, every three to four weeks during peak season.
Water Irregularly
High soil moisture during the summer can attract adult beetles to a lawn to lay their eggs. You can’t do much about rainfall patterns, but you can avoid overwatering your lawn. Instead of watering on a set schedule, check the dampness of your soil and only irrigate when it’s dry. Then, water to a depth of 6 to 8 inches, which will encourage grass roots to grow deeper and stronger in search of water.
Raise Your Mower Blades
Particularly in the summer, let your grass grow a little longer than you normally would — at least 3 to 3.5 inches. Not only will this help keep weeds from growing, but it will also act as a safeguard against grub damage. Taller grass has a higher amount of root mass and can better withstand any grub activity.
Use Preventive Insecticide
If you aren’t able to kill off the adult beetles before they lay eggs, you can purchase a pesticide that will kill the eggs themselves before they hatch. Insecticides that contain imidacloprid are good preventive products.
Fertilize in the Fall
In addition to grub prevention, it’s also a good idea to strengthen your grass. A healthy, well-fertilized lawn will be better able to prevent or survive a grub infestation. Cool-season grasses, like those grown most places in the United States, need feeding in the fall to bulk up before going dormant in the winter.
How to Get Rid of Lawn Grubs
Using Nematodes
If you hate the damage that grubs do to your lawn but you aren’t sold on chemical insecticides, you can try introducing organisms to your lawn that will kill the grubs without harming any plants or wildlife.
Nematodes are microscopic worms, and a species of nematode called Heterorhabditis bacteriophora acts as a parasite to white grubs. Once it has infected an insect, the nematode releases a bacterium that kills the grub within 48 hours.
You can purchase these nematodes online or at many home and garden stores. The packaging will contain directions on how to apply them to your lawn, but usually you’ll add them to water and spray the mixture over your grass. Do this in late summer or early fall, and reapply two weeks later for the best results. Bright sunlight can kill these worms, so apply them in overcast or rainy weather. Nematodes work best for pest control in moist soil, so keep up with your watering.
Although the grubs will die soon after the nematodes infect them, this solution can still take a while to work its way through your lawn. Additionally, using nematodes is a heavy time commitment, so it’s not a quick fix.
Nematodes will, however, help balance the microorganisms in the soil and process nutrients into forms plants can absorb, so they may be worth your time.
Applying Insecticide
Insecticides are highly effective against lawn grubs. They will, however, kill off most beneficial insects in your lawn, in addition to soaking the soil with toxic chemicals.
When the infestation is severe enough, though, a grub killer may be your best choice to save your lawn. When applying the insecticide, you’ll need to decide between a preventive and curative approach. These products will only remain effective in the soil for two to three weeks, so proper timing is essential. Perform inspections around areas that get a lot of sun to see if you need curative treatment.
Curative treatment takes place after the grubs have hatched, which is usually in late summer or early fall. Lawn grubs are easiest to kill when they’re young, so early to mid-August is usually the best time to apply a curative insecticide.
These products will only remain effective in the soil for two to three weeks, so proper timing is essential. Perform inspections around areas that get a lot of sun to see if you need curative treatment.
Preventive treatment, on the other hand, doesn’t rely on such precise timing and inspection. Preventive products remain active in the soil for up to two to three months, so you can apply them in late spring to take care of any eggs or newly hatched grubs.
The drawback here is that you may be treating a problem that isn’t coming, and you’ll find you’ve drenched your soil with long-acting chemicals for nothing. Preventive approaches work best when you can pinpoint signs of grubs.
Organic Ways to Get Rid of Grubs
Using chemical grub control products isn’t for everyone. Fortunately, there are a few organic methods to getting rid of grubs.
Using predatory insects like beneficial nematodes is one way of killing grubs organically, but there are others. One risky approach is letting your lawn dry out to deprive the eggs of moisture. Cool-season grasses go dormant in the summer when eggs are hatching, so you still may be able to revive the grass in the fall, but you do risk damaging your lawn.
Neem oil is a vegetable oil made from the pressed seeds of an Indian evergreen tree. Although it’s toxic if swallowed, it’s used in cosmetics in some parts of the world, but in the U.S., it’s primarily used as an organic pesticide.
Neem oil won’t harm pets, earthworms, or most beneficial insects, and it’s biodegradable, so some homeowners prefer it to synthetic pesticides. It can also kill certain types of lawn fungus.
Another organic curative pesticide, milky spore, is a bacterium that’s lethal to Japanese beetles. It’s commonly sold as a powder that both grubs and adult beetles will ingest. The insects will usually die off between one and three weeks after consuming milky spores. However, it is only effective against Japanese beetles, not chafer beetles, so be sure you know which species you’re dealing with. Milky spore are also best at controlling grub populations, not removing them completely, and it can take several growing seasons to become widely effective.
Identifying Grubs
When people refer to “lawn grubs,” they’re usually talking about white grubs, which are the larval stage of many different types of beetle. These grubs have soft, white bodies that tend to curl into a C-shape when disturbed. They may be anywhere from ⅜-inch to 2 inches long, depending on the species of beetle. Some of the types of beetles that are most likely to introduce grubs into your lawn include:
- Japanese beetle grubs: The Japanese beetle species is most common on the east coast and is notorious for eating nearly any kind of plant it comes into contact with, leaving people searching for ways to remove Japanese beetles from their gardens and yards.
- Masked chafer: Several species of masked chafer act as pests that damage crops and lawns across the country.
- European chafer: Also known as June bugs or June beetles, these beetles tend to infest cool-season grasses.
Not only are these adult beetles destructive, but their larvae can do plenty of damage while still below the soil’s surface. These grubs feast on grass roots, creating widening, irregular brown patches of grass. The beetle larvae also attract animals like raccoons, moles, and birds, which love to snack on the bugs. These animals — particularly moles — can destroy your lawn while digging for grubs to eat.
If you suspect your lawn may be harboring a grub infestation, perform an inspection. Grub-related dead patches tend to show up in the fall, so if you saw a large number of adult beetles during the spring or early summer, give your soil a check.
To do this, pull up the turfgrass around damaged areas and look through the top two inches or so of soil. If there aren’t any damaged places yet, randomly spot-check your yard. If you find more than six to 10 grubs per square foot, you should consider treating your lawn.
Hiring a Professional Exterminator
If you’ve tried some of the above methods and found them ineffective, or if you’re dealing with a severe infestation, there’s no shame in calling in the professionals.
A lawn care company will be able to analyze the problem and provide a comprehensive solution, and its technicians will have the right training and equipment to implement it.
TruGreen gets the reviews team’s recommendation as the preferred nationwide lawn care company.
Top Pick: TruGreen
TruGreen offers a specific grub control and prevention service. A technician will check your lawn for adult beetle activity in the spring to help determine whether treatment is needed. If so, TruGreen will apply a preventive product that will kill eggs and newly hatched grubs come summer.
TruGreen also offers several comprehensive annual lawn care packages. These work to repair grub-related damage and boost the health of your lawn. TruGreen’s services are offered in all states, excluding Hawaii and Alaska.
Final Thoughts
Lawn grubs are the larvae of beetles. These beetles, including Japanese grub beetles and June beetles, lay eggs under the soil’s surface. These eggs hatch and feed on the root systems of your grass, often leaving expanding brown patches. Other signs of lawn grubs include seeing adult beetles and seeing increased animal activity in your yard.
You can use chemicals or natural solutions to DIY get rid of your grub problem, but if the infestation persists or becomes larger than you want to handle, don’t hesitate to call a pest control expert to help.
FAQs About Getting Rid of Lawn Grubs
You can opt for natural solutions — like beneficial nematodes, milky spores, or avoiding watering for about a month — to limit the grub population on your property. Applying chemical treatments or hiring a company like TruGreen to apply chemicals yields faster results usually but can be unsafe for children and pets.
Lawn grubs are a natural part of the ecosystem on your property, and they’re beneficial in small numbers. The grub population can get out of hand naturally, or if you overwater your lawn or have bare patches that allow beetles to lay eggs.
Grub activity can be partially identified by signs above ground. Signs can include brown or dead patches of grass, increased animal activity on your lawn, or dead grass that’s easily pulled out with roots attached. In all cases, though, you’ll need to manually dig up a part of your grass to check for grubs, as other issues could cause dead or weak grass. It may be smart to check your lawn annually to prevent grub populations from arising.
The lifecycle of lawn grubs takes about a year. Adult beetles lay eggs in the soil during early to mid-summer, which hatch in around two weeks. In their larval state, grubs go through three phases called instar. The first instar are new-hatched grubs, while the second is where grubs grow larger and become more active feeders. Grubs in the third instar are the most destructive to lawns, and this stage lasts from summer through fall and winter.
Grubs then enter the pupal stage, which lasts for two weeks, and emerge from their pupa as adult beetles which live for several weeks.
Understanding the lifecycle of grubs is important to understanding how to effectively treat an active infestation, or prevent one from forming.
You can use chemicals to get rid of lawn grubs. Curative and preventative pesticides can both be efficient in killing off grub populations. Curative chemicals treat existing grub colonies, while preventive chemicals treat future populations.
