How to Prevent and Deal With Lawn Grubs

Lawn grubs are pests that have the power to destroy your lawn. If you have just one or two, you can rest easy. But in large numbers. as they feed on grass roots, they cause sections of the lawn to die. Since they hide beneath the lawn's surface and are difficult to spot, they may ruin it before you know they're there. Luckily, there are ways to eradicate them before they cause widespread damage.

Read on to learn how to remove lawn grubs and keep them from returning.

Identifying Lawn Grubs

A grub is the soft. wriggly and wormlike larva of a beetle. They measure about a 1/2-inch long, are white, and are usually found curled up into a C-shape. Lawn grubs have soft bodies with legs near the head. A grub may be the larvae of the masked chafer or European chafer, Japanese beetle, or other beetle species. 

What Do Grubs Turn Into?

Grubs eventually become adult scarab beetles, which emerge from the soil to mate and lay eggs. The adult beetles don't do much damage to yards. Serious damage comes to your lawn, ornamental grasses, and flowers when the adults hatch their eggs, which turn into these problematic, hungry little grubs. Scarab beetles with stout, metallic bodies will emerge to mate and lay eggs in early summer to midsummer.

Dung beetles, which are scarab beetles, are not dangerous to your yard since they feed on feces and are beneficial to soil. However, there are a few different types of pesky scarab beetles that grubs can turn into, including:

• Asiatic garden beetles
• Black turfgrass ataenius
• European chafers
• Green June beetles (June bugs)
• Japanese beetles
• Northern masked chafers
• Oriental beetles
• Southern masked chafers

How to Know if You Have Lawn Grubs

Grub damage can appear in two ways. First, small irregular patches of a lawn will appear brown, dry, and wilted. Damage also occurs when raccoons and crows tear up the lawn to feed on grubs. Both types of damage can be extensive during a severe outbreak.

If you can pull sod away from the ground, the root system may have been eaten by grubs. Cut into the soil and look for their presence. More than ten grubs per square foot is a red flag. 

The presence of grubs may indicates that beetles are laying eggs on your lawn. Tan-colored chafer beetles are active just after sundown, and Japanese beetles can be seen flying during the day, feeding on ornamentals, for example. 

Types of Lawn Grub Control

IPM Program

An integrated pest management (IPM) program—also known as integrated pest control (IPC)—uses a combination of methods to control garden pests. It incorporates preventive measures, regular monitoring for pests, environmentally friendly control methods, and the responsible use of pesticides.

An active IPM program is the best plan for dealing with any lawn pests. Periodic scouting is the best defense, mainly when grub eggs are laid in late June.

If you have cut into the soil and determined an outbreak has occurred, an insecticide such as Dylox could be used. (Insecticides such as Merit help prevent grubs in the egg stage.) It's also best to wait until a new lawn is established before applying grub-killer chemicals.

Organic

Keeping your soil healthy with the right type of organic matter can deter grubs.

Milky spore is a naturally occurring bacterium that can help control grub populations in certain conditions. When the soil is inoculated with milky spores, the grubs inadvertently eat the spores while feeding and die, releasing millions more spores. It can be a lengthy process, but it is organic.

Some nematodes are natural enemies of white grubs. There are many different types of nematodes, some beneficial and others not. For example, beneficial Heterorhabditis bacteriophora (Hb) nematodes are watered into the soil to introduce a natural grub predator. 

How to Repair Lawn Grub Damage

Because the grubs feed on the roots, grass will need to be started from scratch after treatment. Just treat the area like any other bare patch repair, and be certain to keep the seed moist while germinating. Here are the basic steps:

• Rake and remove loose and dead patches of lawn.
• Aerate your lawn.
• Reseed your lawn.
• Adequately water seeds to establish roots.
• Keep an eye on flipped pieces of new lawn; just flip them back over.
  

Billbugs

Billbugs are not scarab beetles; grubs can also become destructive pests. Billbugs are prevalent in most of the United States except in Florida. Adult billbugs are creamy or brown but not metallic. They chew holes in the grass where they lay their eggs. Adults and their larvae are equally damaging since they feed off the grass roots.

Lawn Grub Prevention

The best defense against lawn grubs is to maintain a healthy lawn. When you have strong grass that is tall and thick, beetles will be less likely to lay eggs in it. Here are some tips to keep your lawn as healthy as possible.

• Avoid overwatering your lawn. Beetles favor moist conditions when laying eggs.
• Seed any bare patches quickly and allow new grass to germinate. Grubs enjoy lawns with sparse growth.
• Fertilize properly to keep the nutrients balanced. This will help to resist pests and diseases.
• Keep the blades mowed high, at least three inches or taller. This encourages a larger root mass that is more tolerant of grubs.
• Test the soil for lawn grubs every other year or more often if you've had a grub problem before.
• Use preventive pesticides. Applied in the spring before grubs have hatched, these will keep future grubs from taking over your lawn.