Issue 9, June 17, 2011

Burrowing Sod Webworm

Burrowing sod webworm has been reported in a couple of locations during the past week. In neither location was there obvious damage. The damage it causes is similar to that caused by other sod webworms in that the larva feeds on grass blades at night, causing indistinct brownish turf areas due to thatch showing. Any of several insecticides provides effective control. Subsequent irrigation usually restores the turf's health.

Most sod webworm larvae create horizontal silk-lined tunnels in the thatch where they hide during the day. Burrowing sod webworm constructs a vertical tunnel. When the larvae are reaching maturity, they construct very thick, white tunnel linings. Insectivorous birds such as starlings, red-winged blackbirds, cowbirds, and robins commonly feed on the larvae at this time, and in the process of pulling the larvae out, they also pull out this thick burrow lining. The birds eat the caterpillars but leave the burrow lining on the turf surface. This white lining is about 2 inches long by 1/4 to 1/2 inch wide. From a distance, they look like cigarette butts scattered all over the lawn. (Phil Nixon)

Phil Nixon

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