The 7 Most Common Signs of Lawn Damage From Grubs

We work so hard to keep our lawns lush and green. From feeding to weeding, it’s almost a full-time job. That’s why when lawn grubs feed on our grass roots and damage the yard, it’s enough to make us want to pour concrete over the whole thing and call it a day.

Sorry, am I on my own there?

Anyway, this guide will explain some of the most common signs of a grub infestation. You’ll have a better idea of what to look for and even how you might be able to prevent damage in the future.

What are Grubs, and How do They Damage Lawns?

Grubs are the larval stage of most common beetle species. They look like small white worms with segmented bodies, and they usually have brown or tan heads. When you unearth them, they usually curl up into the shape of the letter C. And these little grubs can do a lot of damage.

How Do Grubs Damage Lawns?

Grubs damage lawns by feeding on the roots of the grass. Beetles lay eggs under the soil surface and as the eggs hatch, the grubs emerge. They then begin feeding on the grass roots, disconnecting the blades of grass from the root systems. This prevents the blade from getting the water and nutrients it needs from the soil, ultimately killing the grass.

What Types of Beetle Grubs Cause Lawn Damage?

There are many types of beetle grubs that can cause lawn damage. The following are some of the most common grub species, but the cause of an individual lawn’s damage might depend on the region:

Japanese Beetle Grubs

Japanese beetles and their grubs have a one-year life cycle. They overwinter deep in the soil and move up near the soil surface in the spring, developing into adult beetles. Adult beetles emerge in early summer, feeding on plants in the area and mating. They then lay eggs in the soil several times throughout the late summer and early fall.

About two weeks after laying, the eggs hatch, and a new wave of grubs feed on grass roots in the soil, resulting in noticeable damage in late summer or early fall. These grubs will then move deeper into the soil as the temperatures drop.

May-June Beetles

May or June beetles and their grubs are more complicated than Japanese beetles, mostly due to their three-year life cycles. In the first year, adult beetles lay eggs as they emerge from the soil in May or June. Grubs hatch from those eggs and the grubs feed and move through the early larval stages, and the damage usually isn’t noticeable.

In the second year, the feeding ramps up considerably. These white grubs move closer to the soil surface and start feeding on grass roots. At this point, these grubs are in the third of the larval stages, and they cause considerably more damage than the year before. As the weather cools, these bugs move deeper into the soil to overwinter.

In the third year, these grubs move back up the soil surface and feed through fall. The mature larvae will emerge as adult beetles the following spring. Strangely enough, however, these beetles are all typically in the same stage at the same time in a region. For this reason, grub-damaged lawns usually appear once every three years.

7 Signs of Lawn Damage from Grubs

There are certain signs that homeowners can watch for that may indicate a growing grub population. The following are some of the most telltale signs.

You Have Patches of Brown Grass

If you’ve noticed patches of yellow or brown grass, this could be an indicator that there are grubs at work under the grass level. These dead patches are caused by the grub feeding on the root system, disconnecting the turf from the water and nutrients in the soil. The grass will slowly begin to curl, turn yellow, and then turn brown.

You’ve Seen Animals Dig Up the Lawn

If you’re noticing animals in the yard like skunks, raccoons, and lots of birds, as well as turf damage from them rooting for bugs, there may be a white grub problem. These animals love grubs and will dig through the soil to find them. If there are animals returning night after night, they might be using your yard as an all-you-can-eat grub buffet.

The Grass Feels Bouncy or Spongy

As grubs attack the root systems, the turf above will begin to feel bouncy or spongy as you walk across it. Noticing a little extra spring from the ground could be an indicator of severe damage caused by grub problems.

The Grass Pulls Up Easily

This is a weird one. If you’re able to reach down into the soil and easily remove the grass or turf, there’s a good chance there is a grub problem. As grubs destroy the root system, they disconnect the grass from the soil. This allows the homeowner to pull the turf up almost like new sod.

Lots of Moths or Beetles Flying Around at Grass Level

If you’re starting to notice a lot of moth-like bugs or beetles flying around at the ground level, it may be that these adult beetles may have just emerged from the pupal stage. Or, they could be looking for an area to lay eggs. Healthy turf can handle these eggs and even some grub activity for a while, but as grub populations rise, lawns can suffer severe grub damage.

The Grass Looks Like It’s Going Through a Drought

Grub damage can appear very similar to drought stress, and there’s a reason why: The grass is thirsty. In both cases, the lawn may appear as dead grass, as drought causes healthy turf to go into a stage of dormancy, while a grub-damaged lawn will actually be starving for water and nutrients. The difference is that drought damage is usually reversible while grub damage might not be.

The Square Foot Test

If you suspect there is some grub activity at hand, there is a surefire way to check: The Square Foot Test. With a clean spade shovel, dig up a one-square-foot section of soil in multiple areas of the lawn. Pull back the turf and count the grubs. A few grubs aren’t a big deal. More than five grubs could indicate an impending grub infestation. Ten or more grubs are a sign that there is currently a grub control issue and homeowners need to consider their next steps.

How To Treat for Grubs In Your Lawn

If the white grub populations are too high in your yard, there are some things you can do to control them. The following are some of the most effective methods for controlling grubs, and some homeowners might find it takes a combination of these methods to kill grubs in their yards.

Apply Grub Control Products

The first step in getting rid of grub problems is to prevent them from even occurring by using preventative grub control products. These products can be applied to the soil in early spring to early summer, and they attack the eggs and grubs before they’re able to hatch and cause an issue.

Apply Grub Killer

Grub killer products are for active infestations. These products kill white grubs and other pests on contact, but they usually need to be watered in by a hose or an irrigation system immediately to allow them to soak into the soil and get to work killing grubs and other pests.

Invite Natural Predators into the Yard

Inviting birds into your yard is one of the best ways to stay on top of a grub issue. Birds will do less damage to the soil than a skunk or raccoon, and if you invite enough of them with bird feeders, bird baths, and birdhouses, these flying pest control technicians can decimate white grubs and prevent grub damage in the lawn. This is an integrated pest management method that makes perfect sense for most home lawns.

Apply Milky Spore

Milky spore is a bacteria that homeowners can spread in their lawns. The grass soaks up the milky spore, which the grubs then eat, and then the milky spore turns their insides into liquid until they die.

Introduce Beneficial Nematodes

Beneficial nematodes can be applied to the soil, and if they’re exposed to irrigation immediately, they’ll soak into the soil and start hunting for white grubs. This might not be the fastest way to control grubs, but it is one of the most natural. Also, beneficial nematodes are available at most garden centers.

Dethatch and Aerate the Lawn

Grubs don’t like being exposed to predators flying overhead. Rather than allowing them to set up shop, remove all of the dead grass and aerate the lawn. This will allow the soil to dry out faster, creating less hospitable conditions for Japanese beetle grubs and May or June beetles in the lawn.

Call a Professional Pest Control Service

Another option is to call a professional pest control service. These pros will show up, assess the issue, and discuss options with the homeowner. Some might even have service contracts that users can sign for ongoing pest control services. Many lawn care companies also offer similar services so it’s worth checking those companies out, as well.

For More Information on Grub Control

If you’re looking for more information on grub control or the products you can use to kill grubs, check out our post on the best grub killers for 2023.

Grub Damage FAQs

That’s a lot of information on grub damage, but there might still be some gnawing questions to answer.

When should grub control be applied?

Grub control should be applied early in the spring as it can prevent grubs from being an issue. These products attack the eggs, making grub control easier than killing.

Are there natural treatments for grub infestations?

Yes, homeowners can try natural products like neem oil, beneficial nematodes, and Milky Spore to get rid of grub infestations.

How bad are grubs for the lawn?

Grubs kill lawns. They disconnect the turf from the root system below, resulting in dry, brown, dead grass.

What chemical products can I use to control grubs in my lawn?

There are a slew of products that you can use, and we covered the best grub killers in this article. However, our favorites are:

• BioAdvanced 24-Hour Grub Killer Plus
• Sevin Lawn Insect Killer Granules
• BioAdvanced Season Long Grub Control Plus Turf Revitalizer

When is the best time to treat for grubs?

The best time to treat for grubs is early spring to early summer, applying a control product that prevents grubs from reaching maturity.

How do I know if I have grubs?

The best way to tell if you have grubs is to perform The Square Foot Test. Simply dig up one square foot of lawn in several areas throughout the property. Pull up the turf and count the grubs. Just a few grubs are fine, while more than 5 is a sign of an impending infestation. Ten or more grubs are a sign of a current infestation.