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Sod Webworms & Cutworms

Sod Webworms

Tropical sod webworms are one of the most destructive pests of St. Augustine grass. The name "webworm" is derived from the insect's habit of lining its tunnel with silk-like material that they produce. Damage from these lawn-invading pests happens quickly -- seemingly overnight -- and can be similar in appearance to drought. 

Life Cycle

Sod webworm larvae may complete 6 to 10 larval instars. Moths are 0.5 to 0.75 inches long and have snout-like projections on their heads. You see the moths fluttering over the turf and in flowerbed areas nearby. This short-lived moth does not feed on the turf, but it is responsible for laying eggs in the grass. The eggs hatch in 7 to 10 days, and the larvae begin feeding on the turf. 


The larvae (worms) can grow up to 1 inch long and are light green to gray-green with dark spots on their body. Most feeding by sod webworm larvae occurs at night. The second generation of adult moths are active from late July through August. Eggs are laid and hatch into young larvae, which feed through late September and then over winter. Multiple generations of sod webworm can occur on an annual basis. 

Damage to the Lawn

Damage first appears as small brown patches of closely clipped grass. Lawns are particularly susceptible to larval damage during the months of July and August when the temperatures are hot and lawns are not growing vigorously. Large lawn areas may be damaged rapidly if controls are not applied.

Larvae chew off leaves and stems just above the crown. As webworm larvae continue to grow and feed, the injured areas enlarge and coalesce into bigger patches. At first glance, you may think turf disease is at play (brown patch is another typical problem in St. Augustine lawns). However, after a close inspection, you will likely see that the leaves have heavy chewing damage. Young larvae feed along the mid-rib trough of the leaf. Mid-sized larvae chew notches in the edges of leaves, and older larvae will completely strip off the leaves. 

IMPORTANT: The combination of worm damage, hot temperatures and drought may kill off lawns that were already weakened by disease and low mowing.


Recovery is likely for lawns that were in good shape prior to worm damage. Lawns will start to recover once the worms have been killed. 

If you detect this or any kind of problem on your lawn and you are not sure what it is, contact us immediately. 

Even if you had a recent application with us, worms may arise overnight. An insecticide application is required to control this problem. 

The best solution for a late season recovery is to raise your mowing height as high as possible and maintain adequate soil moisture. There is still enough time to provide for at least a partial recovery of lawns that have been damaged by tropical sod webworms. 

Lastly, It is very important to understand that any lawn that is mowed too short will always be more susceptible to many kinds of problems, including fungus, drought, worms and weeds. Grass is a living organism. It needs appropriate watering and mowing practices to be able to fight back against insects, disease, and weeds. The higher the grass is mowed, the better opportunity it has to grow thicker and more resistant leaves. Your involvement is crucial in our efforts to give each and every customer a beautiful, healthy lawn. 


Cutworms can devastate your lawn. These large, plump, grayish/green/brown larvae viciously chew on grass plants. They live on the soil's surface or in the thatch layer. During the day, they burrow into vertical holes to hide. When nightfall arrives, they emerge from their burrowed hole and feed at the rim of the hole. Stems, leaves and roots of grass plants may be injured leaving yellowish/brown dead patches with a hollow hole in the middle of the circle.

The damage looks quite similar to symptoms of dryness, and many homeowners mistakenly assume that a lawn simply needs water to restore a lush, green appearance. Other symptoms to watch for include birds gathering on the lawn, as starlings have a keen ability to locate cutworm larvae. When these birds return frequently to an area, cutworm larvae may be present.



Life Cycle

The adult cutworm appears in the spring as a grayish/brown moth with a 1 - 1 ½" wing span. Adult cutworms do not damage lawns. They lay their eggs in the spring during the night leaving them on grass blades. Larvae emerge and begin feeding as early as June, with damage appearing in June/July. Cutworms actually feed at night on grass blades that they chew off close to the base of the plant. Dead patches of grass begin to appear and may be pulled away easily by hand.

Control for Sod Webworm and Cutworm

Weed Man technicians are trained to identify and treat potentially devastating infestations of sod webworm and cutworm. We only use materials that are applied carefully and precisely at the correct times to be most effective in controlling these serious lawn pests. If you do have these insects, we can protect your investment in your property by promptly treating the problem.