How to Get Rid of Grubs
Grubs feed on the roots of your lawn and plants. Take control before these destructive pests get out of hand.
You may not see grubs in your yard, but that doesn't mean they aren't there. These pests live in the soil for most of their lives, so they aren't visible unless you happen to till up a patch of ground or turn over a couple of rocks. Most yards have some grubs, but you can have a serious problem if you have a large infestation.
What Are Grubs?
Grubs, also called white grubs or lawn grubs, are the larvae of various scarab beetle species (Scarabaeidae). They live all over North America, where they damage or destroy lawns and garden plants. They feed on trees and shrubs, crops, lawns and fruit and vegetable plants.
Grubs feed on organic material in the soil and the roots of grasses and plants. They attract grub-eating crows and other birds, as well as animals like skunks, moles and raccoons that also damage your yard by digging it up to find them — and these pesky diggers may come back for up to a year after you get rid of the grubs because they remember where they were.
Grubs are most commonly the larvae of these beetles:
- Japanese beetles - Iridescent green beetles with coppery-brown wing covers.
- Sugarcane beetles - Dome-shaped beetles with hard, black shells; primarily attack crops like sugarcane and corn.
- European chafers - Tan or light brown beetles that mature to about 1/2" long.
- Masked chafers - Golden brown beetles with darker brown heads and "hairs" underneath the thorax.
- May/June beetles, or June bugs - Reddish-brown to almost black and 1/2-inch to 1-inch long.
- Asiatic garden beetles - Chestnut-brown beetles with an iridescent or slightly velvety sheen.
- Oriental beetles- Light brown to black and similar to Japanese beetles.
Signs of Grubs in Your Lawn
Irregularly shaped brown patches in your lawn are often signs of grub damage. Eventually, the patches can die and become loose enough to pull up since they no longer have roots to hold them.
"Early symptoms of a white grub infestation often resemble signs of drought stress; the gradual thinning, yellowing and wilting of grass or scattered, irregular or dead patches of grass," says Marc Mayer, director of technical operations at TruGreen, a lawn care company. Once the roots are gone, the dead patches can feel spongy when you walk on them. "Watering these areas of your lawn will often mask the injured grass but not eliminate the lawn-destroying insects."
To confirm grubs are the cause of your lawn problems, Mayer recommends pulling or cutting back a section of damaged grass and looking for grubs on or near the soil’s surface. Go 2 or 3 inches deep and remove about a square foot of turf that’s turned brown and dry. "In most cases, lawns will survive if the soil has a lower population of grubs, or five to six grubs per square foot, especially if the lawn is healthy and irrigated," he says. If you have more than a half dozen grubs per square foot, it's time to get rid of the grubs or act to prevent them.
The Life Cycle of Grubs
Depending on the species, female adult beetles lay eggs in the soil from about June into August. "Once these pests reach the larvae stage, they will start chewing on the roots of your grass and possibly vegetable plants in your garden," says Mayer. They typically feed from September to November and from March to early May, he adds, and feed less often in the spring.
In the winter, the grubs burrow into the ground and go dormant, only to return and start eating again the following spring. After they've finished feeding, the larvae become pupa and burrow back into the ground for several more weeks. Finally, the pupa become adult beetles and re-emerge.
What Do Grubs Look Like?
"Adult grubs are typically easier to distinguish than larvae, which look fairly similar in appearance," Mayer says. "Generally, white grubs have creamy-white to gray-colored bodies, brown heads and six distinct legs, and they can usually be found in a curled-up position in your lawn." They range from 3/4-inch to 2 inches long.
How to Get Rid of Grubs
Keeping your lawn healthy by properly mowing and watering can help it stand up to grub attacks. Dethatching and aerating make it easier for any products you use to reach the grubs, since they usually live in the top 2 inches of soil.
If your grub population is too high, try one of these methods. (Always read the labels of your products and follow all directions. Wear safety goggles and a face mask if you’re using products that come in small granules that create dust.)
- Apply milky spores (Bacillus popilliae). Sold as a powder, milky spores are ecologically friendly bacteria that target only Japanese beetle larvae. One disadvantage is that milky spores can take a few years to eliminate the grubs. This biological control can last for years but usually needs to be applied a few times a year for the first two or three years or as directed on the label.
- Use beneficial nematodes. Buy these tiny worms from a home and garden center or online. Release them very early in the day or in the late afternoon to keep the sun from burning them up. These little parasites eat grubs and are sometimes used in combination with milky spores. They may need to be applied once or twice a year for several years to control a large infestation.
- Pesticides. Look for pest control chemicals sold at lawn and garden centers that target grubs, and use them with caution. Some of these toxic products also kill beneficial insects, and runoff from treated areas can pollute ponds, creeks and other waterways and get into the water table. Do not use them around pets or children. Some chemicals kill the larva but not the pupa, so read the label to know what time of year to apply them — usually in late summer or early fall.
- Spray with a borax mixture. Some homeowners get rid of grubs by spraying infested areas with a tablespoonful of borax, a common household cleaner, mixed with a quart of warm water. Be careful; borax can damage sensitive plants and your grass if you spray too much or too often. Test it on a leaf or two first and watch your plants for a couple of days before you apply it to entire plants. Spray only the areas where you see grubs.
- Neem oil. Use a Neem oil spray or drench during the egg-laying season.
- Spray with diluted dish soap. Some homeowners mix one tablespoon of dishwashing soap (Dawn is often recommended) with one quart of water and spray it directly on any grubs they see or on parts of a lawn damaged by grubs. "Be careful with some home remedies since recommendations like soap at higher concentrations mixed with water can actually burn or damage turf, too," says Mayer.
- Let your lawn dry out for a few weeks. Beetle eggs need moisture, so you can try killing the eggs by not watering your lawn for a few weeks if you're already in a drought. The grass will turn brown, but most healthy lawns will resume growing when you start watering again. If you’re not sure whether your type of grass can dry out and come back, check with your local extension service for advice.
- Welcome birds. Grub-eating birds are your natural allies. Add some bird feeders, bird houses and a bird bath to your yard to attract them. Have a flock of chickens, geese, ducks or guineas in your yard? They also love grubs.
- Call a professional lawn care company. They can help if you have a heavy infestation, don't feel comfortable using pesticides or need more than DIY treatments.