Grub Worm Control for Grass Lawns

Grubs are the larval stage of beetles, and can cause damage to turf lawns.

According to the U.S. Department of Agriculture, grubs are the most damaging turf pest in the U.S., and cause $234 million in damage each year. Not only do they feed on the root system of the grass, but they attract other small pests that dig in the lawn to feed on the grubs. There are several ways to control grubs, including chemical and biological applications.

Grubs

Grubs are the larval stage of many different types of beetles, including the Japanese beetle. In the spring, the female beetle burrows into the warm, moist soil of turf lawns. She typically lays 40 to 60 eggs a season. These eggs will eventually hatch and the grubs will remain in the soil until they mature. The grubs feed on the root system of the grass, destroying it.

Effects

Grubs do the majority of their damage during the summer months when they are actively feeding. They feed on the roots of the grass, which will eventually die. The damage usually does not appear until the fall, when it is too late. Grub damage appears as irregular, brown patches in the lawn. The dead grass will peel away from the soil very easily. Not only do the grubs damage your lawn, but they attract other small pests, such as mice and moles, which dig into the lawn to feed on the grubs.

Solution

Grub control can either be aimed at killing the beetles that lay the eggs that become grub worms, or on killing the grubs themselves. This can be done either with chemical treatments or environmentally safe biological treatments. Both can be effective ways of controlling grub worms.

Chemical Insecticides

Chemical insecticides require timely application. They are most effective when applied before the eggs are even laid, or when the grubs are very small and feeding near the surface of the soil. Otherwise, these chemical treatments are not effective in controlling grubs. Two of the most effective chemicals used to control grubs are Merit (imidacloprid) or Mach 2 (halofenozide). They must be applied in a short window of time in late summer or early fall. They are available in liquid or granule form, whichever you prefer.

Biological Treatments

Many people do not like to use chemical insecticides because of the potential harm that they can cause to the environment. Some environmentally safe biological treatments are effective against grubs. The first biological treatment is bacterial milky spore disease. The powder spores of this bacterium are applied to the lawn. The grubs ingest this bacterium, which kills them, and as the grub decomposes, it creates more spores. The downside to this treatment is that it takes 2 to 3 years to build up the spore count in order to be effective. Another biological application is entomopathogenic nematodes. These are tiny, parasitic worms that are applied to the lawn, and release bacteria that kill the grubs. The lawn must be irrigated before and after treatment to be effective.

References

• american-lawns.com: Grubs
• Pestproducts.com: White Grubs
• LivingWithBugs, LLC: White Grubs in Gardens and Lawns