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Insect Pests of the Lawn

Three c-shaped grubs on soil, with a small, medium and large from left to right
White grubs L to R: Japanese beetle, European chafer, and June bug. Photo: David Cappaert, Bugwood.org

The number of insect species that will feed on or damage home lawn grasses is limited. Some feed on the roots of grasses, some on the leaf blades, and others just happen to use areas of the lawn for nesting, causing no significant damage to plants. If you understand the signs and consequences of insect damage to your lawn, you will save time and money that you might have spent on insecticide treatments.

Reducing your reliance on pesticides helps protect surface waters (LI Sound, Great South and Peconic Bays, the ocean and local streams and ponds) and underground aquifers, which serve as our everyday drinking water.

Robert Moses Causeway bridge over the Great South Bay, Long Island
Long Island's Great South Bay and Robert Moses Causeway bridge. Photo: J. Gangloff-Kaufmann
white c-shaped grub in the palm of a hand
White grub in soil. Photo: J. Gangloff-Kaufmann

White grubs (beetle larvae) – Many scarab beetles start life as c-shaped white larvae, called grubs, that live and feed in the soil root zone. Some pest species feed on and damage the roots of lawn grasses. They prefer moist soil, such as low spots in a lawn. In high enough numbers, white grubs can damage roots and kill lawn grasses. A key sign of white grub feeding is brown damaged areas that can be peeled up, as if they were mats of sod. If you suspect grubs, use a shovel to cut a square foot of turf and lift it to check for grubs in the top 2 inches of soil. Healthy turf can tolerate 5-10 grubs per square foot. Setting the mower at its highest mowing height can improve grass health and white grub tolerance.

For a deeper dive into white grub ecology and management see “What’s Bugging You: White Grubs” and “Grubs in Your Lawn? A Guide for Lawn Care Professionals and Homeowners”.

Two small chinch bugs on a blade of grass
Hairy chinch bug. Photo: D. Shetlar, Ohio State Univ., Bugwood.org

Chinch bugs are true bugs, related to stink bugs and aphids, but small as adults (4mm or 1/16”) and tiny as nymphs. They feed on  plant juices with a needle-like mouth causing grass blades to yellow and then turn brown. More active in sunny, dry areas, chinch bugs are not as problematic in wet cool weather. Raise your mowing height and avoid applying fertilizer in early summer to reduce chinch bug numbers and damage. Overseed your lawn with endophyte-enhanced grasses, which are toxic to chinch bugs, keeping their numbers in check.

For a closer look at chinch bug ecology and management see Penn State Extension’s page “Chinch Bugs in Home Lawns”.

a small skinny moth sitting along a blade of grass
Crambus moth. Photo: W. Cranshaw, Bugwood.org

Sod webworms are the caterpillar (larval) stage of a few species of “lawn moths”, or "crambid snout moths", a group of skinny, pale brown moths less than an inch long. You might see moths flying in a zig zag motion over the lawn at dusk. Sod webworm larvae chew off grass stems just above the base of the plant, causing dead patches, which can be disguised by drought stress or dog spots.  If you are concerned about sod webworms, check to see if they are present by using a soapy water flush described by North Carolina State University.

a single ant on a white surface
Field ant. Photo: J. Berger, Bugwood.org

Ants can be beneficial or occasionally problematic for lawns. Generally, ants are beneficial insects that create extensive tunnel nests in the soil, bringing oxygen and water to the root zone. They also feed on other arthropods, including pest insects of lawn grasses. However, some ants can damage lawns by burying grasses with excavated soil or actively nurturing aphids that live underground and feed on plant roots. For the most part, this type of damage is rare and there is usually no need to control ants in a Long Island home lawn.

fuzzy yellow bee sticking its head up out of a hole in the soil
Cellophane bee in sandy soil. Photo: M. Frye

Ground nesting bees emerge in the early spring from soil tunnels created the year before. They inhabit dry sandy areas where plants are thin and soil is visible. While they might appear in large numbers, flying over the lawn surface, these bees are beneficial early pollinators and not harmful to the soil, lawn or people. The best method to limit their activity in any location is to restrict access to soil, using mulch or plants. Improve soil conditions and seed your lawn to grow more dense turf that is less attractive for ground bee nesting.

a large striped wasp sitting on a rock
Cicada killer wasp. Photo: M. Frye

Cicada killer wasps, among the largest wasps in the Northeast, prefer sandy dry soils for digging tunnels and galleries where eggs are laid. These mostly harmless insects capture, sting and drag cicadas back to their tunnels as food for developing larvae. While females are busy digging tunnels and harvesting cicadas, stingless male wasps are busy guarding the nest openings of females and this hovering behavior is not a threatening gesture. Learn more about cicada killer management at our “What’s Bugging You: Cicada killer wasps” page.

seven tiny black weevils in the palm of a hand
Annual bluegrass weevils are tiny. Photo: T. Billeisen, NCSU

Weevils are a common type of beetle with a long snout. Two types, the annual bluegrass weevil (ABW) and the bluegrass billbug (BGB) are pests of lawns and other turfgrasses. ABW tends to damage high maintenance turf, like that on golf courses. Low maintenance lawns can be damaged by BGB. Females of both species chew holes into grass stems and insert eggs. Developing larvae feed inside the stems of grasses killing the plants. In home lawns BGB is most damaging on Kentucky bluegrass. In areas with persistent dieback of grass from weevils, reseed the lawn with tall fescue (sun), fine fescue (shade) or perennial rye. Using cultivars with endophytes, symbiotic fungi that are toxic to chewing insects, can greatly reduce weevil damage. 

For more guidance on bluegrass billbugs, see: Billbugs in Home Lawns, by Penn State Extension

For more guidance on annual bluegrass weevils, see: Turfgrass: Annual bluegrass weevil

Other turfgrass pests: