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Cutworm & Sod Webworm

What are Cutworms?

Cutworms are large, plump, dull-colored grayish-green-and-brown larvae that viciously chew on grass plants. Cutworms live on the soil surface or in the thatch layer. During the day, they burrow into vertical holes to hide, and 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 the lawn requires only water to restore the lush-green appearance. Other symptoms to watch for include birds - starlings have a keen ability to locate cutworm larvae. When these birds return frequently to an area cutworm larva may be present.

Cutworms are

The Lifecycle of Cutworms

To control an insect population we must understand its habits and life cycle. The adult cutworm appears in the spring as a grayish/brown moth with a 1–1 ½ ” (2 ½–4 cm) wingspan. 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.

What are Sod Webworms?
The immature larvae stage of the Sod Webworm is as long as 3/4 of an inch and are dirty white or tan colored and frequently have rows of dark spots along their back. Pictured below the larvae is the adult moth that does not harm the lawn.

Sod Webworm can damage your lawn severely. The immature larvae stage of the Sod Webworm is as long as ½” and are dirty white or tan-colored, and frequently have rows of dark spots along their back. Sod Webworm adults are small tan moths, ¼ –¾” (½ –2 cm) long. The adults are frequently seen darting across the lawn, especially when disturbed. The adult moths do not harm the lawn.

As with Cutworm damage, the symptoms of damage appear similar to that of dryness. As larvae, they construct tunnels or burrows through the thatch layer, sometimes extending into the soil. The name Webworm is derived from the insect’s habit of lining its tunnel with silk-like material that they produce.

The Lifecycle of Sod Webworm

Adult Sod Webworms emerge from the lawn in May or June flying mainly during the evening hours laying eggs randomly throughout the lawn. The larvae emerge from the egg and begin feeding immediately. Damage is caused by larvae chewing off grass stems and leaves while feeding during the summer and into early fall. The dead patches of grass pull away easily in clumps, revealing masses of silk with the green excrement pellets left by larvae. Severe damage may result in September if the population throughout the summer builds up.

Controlling Cutworm and Sod Webworm

Your Weed Man is a trained specialist and is capable of identifying both damaging insects. He can recognize the difference between a simple drought problem and a serious insect infestation. Your Weed Man uses materials that are applied carefully and precisely at the correct times to be most effective in controlling these serious lawn pests.

Call Weed Man and he will inspect your property free of charge! If you do have these insects, he can protect your investment in your property by promptly treating the problem. If your brown patches are due to lack of water, he can advise you on correct watering procedures.

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Main Service Areas

DeVries services the greater Grand Rapids area with the finest commercial and residential outdoor care. Service areas vary.

Contact us at 616-669-0500 for more information.

The crew did a great job picking up leaves.

S.H.

Jenison

Turf Tip

Summer Dormancy

Dormancy is one of the mechanisms nature has developed to help plants survive stressful conditions. Summer dormancy occurs in a lawn when grasses are exposed to an extended period of heat and lack of moisture during mid-summer. Learn the signs of summer dormancy and how to avoid it here.
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