Few things are more frustrating than watching your lawn turn brown in patches for no obvious reason. You're watering, mowing at the right height, and the rest of the yard looks fine — but these dead-looking areas just keep spreading. If that sounds familiar, there's a good chance grubs are the culprit.
What Are Grubs?
Grubs are the larval stage of various beetle species, most commonly Japanese beetles, June bugs, and European chafers here in Indiana. Adult beetles lay their eggs in lawn soil during the summer months. Those eggs hatch into small, white, C-shaped larvae that live just below the soil surface and feed on grass roots.
A few grubs in your lawn are normal and usually don't cause noticeable damage. Every lawn has some. The problem starts when populations get high enough — typically more than 10 grubs per square foot — that they're consuming roots faster than the grass can replace them. That's when you start seeing damage.
Signs of Grub Damage
Grub damage can look a lot like drought stress or disease at first glance, which is why it often goes undiagnosed until it's severe. Here are the key signs to watch for:
- Irregular brown patches that appear in late summer or early fall and don't respond to watering. These patches often start small and expand over a few weeks.
- Spongy, soft turf. Walk across a damaged area and it will feel noticeably spongy underfoot because the root system has been eaten away and the turf is no longer anchored firmly to the soil.
- Turf that peels back like carpet. In severe cases, you can grab a handful of brown grass and roll it back from the soil because there are simply no roots holding it down. This is the classic sign of heavy grub feeding.
- Increased animal activity. Skunks, raccoons, armadillos, and birds will tear up your lawn to get at grubs. If you're waking up to chunks of sod flipped over or small holes dug throughout the yard, animals are likely feeding on a grub population beneath the surface.
- Lots of adult beetles in summer. A large number of Japanese beetles or June bugs around your property in June and July often means a large egg-laying event is underway, which can lead to a grub problem six to eight weeks later.
The Tug Test
The simplest way to confirm a grub problem is the tug test. Go to the edge of a brown or thinning patch — the transition zone between healthy and damaged grass — and grab a section of turf. Pull it firmly upward.
If it lifts away from the soil easily with little to no root resistance, you almost certainly have grubs. Healthy turf should be firmly rooted and resist being pulled up. Once you've peeled back a section, look at the top inch or two of soil. Grubs are easy to spot — they're white or grayish-white, C-shaped, and typically about the size of a quarter when curled up.
Count how many you find in a one-square-foot area. Five or fewer is generally not a problem. Ten or more per square foot indicates a population that's causing damage and warrants treatment.
Preventive vs. Curative Treatments
There are two approaches to grub control, and the right choice depends entirely on timing.
Preventive Treatment (Best Option)
Preventive grub control products are applied in late spring to early summer — typically June through mid-July in Indiana — before the eggs hatch. These products remain active in the soil and kill young grubs as they emerge from eggs and begin feeding.
The active ingredients to look for in preventive products include chlorantraniliprole (which can be applied even earlier, in April or May) and imidacloprid or thiamethoxam (applied in June or July). Chlorantraniliprole is our preferred option because it has a wider application window and is effective at very low rates.
Preventive treatment is the most reliable approach because you're addressing the problem before damage occurs. If your lawn has had grub issues in the past, or if you see heavy beetle activity in your area, an annual preventive application is good insurance.
Curative Treatment (When Damage Is Already Visible)
If it's late August, September, or October and you're already seeing damage, you've missed the preventive window. At this point, you need a curative product that kills larger, actively feeding grubs. The most common curative active ingredients are trichlorfon and carbaryl.
Curative products work, but they have a shorter residual and need to be watered in immediately after application to move the product down to where the grubs are feeding. They're also less effective against mature, late-stage grubs, so timing still matters — the sooner you catch the problem in fall, the better the results.
Best Timing for Indiana
Here's a quick timeline for grub management in our area:
- April–May: Apply chlorantraniliprole-based preventive (earliest option)
- June–mid-July: Apply standard preventive products (imidacloprid, thiamethoxam)
- Late July–August: Eggs hatch, young grubs begin feeding near the soil surface
- September–October: Grub damage becomes visible; curative treatment window
- November–March: Grubs move deeper into soil for winter; treatments are ineffective
The worst time to treat is winter and early spring. Grubs overwinter deep in the soil where products can't reach them, and by the time they move back toward the surface in spring, they're large and nearly done feeding before they pupate into adult beetles.
Repairing Grub Damage
Once you've treated the grub population, you'll likely need to repair the damaged areas. For small patches, loosen the soil, add some compost, spread quality grass seed, and keep it watered. For larger areas of damage, overseeding combined with aeration is the most effective approach — and fall is the ideal time for both the treatment and the repair.
In severe cases where the turf is completely destroyed, sodding or hydroseeding may be the fastest path to recovery.
Let Us Handle It
Grub control is one of those things that's much easier to prevent than to fix after the fact. All Brothers Lawn Squad offers preventive grub control as part of our lawn care programs, and we can diagnose and treat active infestations as well. If you're seeing signs of grub damage or just want to make sure it doesn't happen, reach out for a free quote or call us at (765) 371-4186.