That fat, white, C-shaped creature you dug up is almost certainly a scarab beetle larva, commonly called a white grub. These grubs live in soil, feed on roots and decaying organic matter, and range from ¾ inch to over 2 inches long depending on the species. The bigger the grub, the more likely it belongs to a May or June beetle, a green June beetle, or in rarer cases, something more exotic like a Hercules beetle larva.
What You’re Looking At
White grubs share a distinctive look across species. They curl into a C shape at rest and straighten out when crawling. The body is white to grayish, with an orange-brown head and six small legs clustered near the front. The rear end often appears darker because you can see digested soil through the skin. Full-sized grubs from common lawn species measure ¾ inch to about 2 inches when stretched out.
If the grub you found is noticeably larger than 2 inches, you may be looking at a Hercules beetle larva. Eastern Hercules beetles are among the largest insects in North America, with adults exceeding 2 inches. Their grubs look like oversized versions of typical lawn grubs and develop inside decaying hardwood logs and stumps rather than in turf. They take about two years to complete their lifecycle. Their South American relatives can reach six inches as adults.
Common Species and How to Tell Them Apart
Several scarab beetle species produce large grubs that show up in lawns and gardens. The species matters because it affects how much damage they cause and when treatment makes sense.
- Japanese beetle grubs are among the most common. They complete one generation per year and are medium-sized as grubs. Healthy turf can tolerate up to 10 per square foot, though animal digging becomes a problem at lower densities.
- May and June beetle grubs tend to be the largest of the common lawn species and take 2 to 3 years to mature, feeding for an extra year compared to other grubs. They can completely destroy a root system at just seven per square foot, with treatment recommended at four to five.
- Green June beetle grubs behave differently from other species. They feed on roots and thatch but also crawl above ground to move between feeding spots, which sometimes startles homeowners who see them on the surface.
- Southern masked chafer grubs are more tolerable in healthy lawns. Well-maintained turf can handle up to 20 per square foot before showing symptoms.
Entomologists distinguish species by examining the pattern of tiny bristles on the underside of the grub’s last body segment, called the raster pattern. Without a magnifying lens and a reference guide, most people won’t be able to identify the exact species from the grub alone. The adult beetles are much easier to tell apart.
Their Lifecycle in Your Soil
Most grub species follow a predictable annual calendar. Adult beetles emerge in early summer, peaking around early July, and lay eggs 1 to 4 inches deep in the soil. Those eggs hatch about 10 days later, in mid to late summer. The young grubs feed on roots roughly 2 inches below the surface through mid-October, then burrow down 6 to 18 inches to ride out winter in an inactive state.
In late spring, around late May, they migrate back up and resume feeding for several more weeks. They then pupate 2 to 8 inches below the surface for a week or two before emerging as adult beetles. May and June beetles break this pattern by spending an additional year as larvae, which is why their grubs grow so large. Depending on the stage, they can overwinter as larvae, pupae, or adults.
How Grubs Damage Your Lawn
Grubs eat grass roots. At low numbers, this causes thinning and yellowing that mimics drought stress or poor fertilization. At higher numbers, the root system gets so compromised that you can grab a section of turf and peel it right off the ground like a loose carpet. The soil underneath often feels spongy.
Most healthy, well-watered lawns can tolerate 5 to 7 grubs per square foot without visible damage. Stressed or poorly maintained turf shows problems at lower densities. To check your lawn, cut a 1-foot square section of sod a few inches deep and count the grubs you find. Do this in a few spots to get an accurate picture.
The secondary damage is often worse than the grubs themselves. Skunks, raccoons, armadillos, and other animals dig up lawns to eat grubs, and they can detect grub populations as low as five per square foot. Skunks push their noses into the turf and excavate with their front paws, creating so many holes they merge into large torn-up patches. Raccoons are even more dramatic: they use their paws like hands to peel back entire strips of sod, leaving the lawn looking like someone tried to roll it up. This destruction happens overnight and can be extensive.
When and How to Treat
Treatment timing depends on the grub’s lifecycle. Preventive products are applied in early to mid-summer, before eggs hatch, and work by killing young grubs as they begin feeding. This is the most effective window. Curative products target grubs that are already established and feeding in late summer or early fall, but they’re less reliable because the grubs are larger and deeper in the soil.
By the time grubs have burrowed down 6 to 18 inches for winter, no topical treatment will reach them. And by spring, they’re nearly done feeding before pupating, so the treatment window is short. If you’re finding big grubs in spring, the damage is mostly already done for that generation.
For a biological approach, parasitic nematodes can be watered into the soil to attack grubs. They work best on young grubs in moist, warm soil. Milky spore disease is another biological option that specifically targets Japanese beetle grubs, though it takes a year or more to build up in the soil.
Healthy lawn care is the simplest defense. Turf with deep roots and adequate water tolerates far more grubs before showing damage. Keeping your lawn slightly taller and watering deeply but infrequently encourages root depth that can absorb grub feeding without collapsing.
Grubs in the Garden Versus the Lawn
If you’re finding big grubs while turning over garden soil or compost, the situation is different from a lawn infestation. Many grubs in garden beds or compost piles are feeding on decaying organic matter rather than live roots. Green June beetle larvae and Hercules beetle larvae both prefer decomposing wood and plant material. These grubs are doing useful composting work and pose little threat to your plants.
Grubs found in potted plants or raised beds with vegetables are more of a concern, since they’re confined in a small root zone and can damage plants even at low numbers. Handpicking is usually enough in these settings. Birds, particularly starlings and crows, are enthusiastic grub hunters and will pick them off exposed soil if you leave them on the surface after digging.
Edible Grubs Around the World
Large beetle grubs are a significant food source in many cultures. The African palm weevil larva, a large grub harvested from palm trees, contains about 31% protein and 65% fat on a dry-weight basis, making it one of the most calorie-dense insects eaten worldwide. Aboriginal Australians have eaten witchetty grubs for thousands of years, and sago grubs are a staple protein in parts of Southeast Asia and the Pacific. These are different species from typical lawn grubs, but the basic biology is similar: a large, fat-rich beetle larva developing inside organic material.