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A word from UGA Extension
What to do with turf caterpillars
Ingram Sam
Sam Ingram

Composting class
Effingham County Extension will be hosting a composting workshop Oct. 6 at the Effingham County Extension office. The class will begin at 11:15 a.m. The class will be led by Clarke County Extension agent Amanda Tedrow. Registration is required by Thursday. Those interested can register by calling (912) 856-8997 or email The class is limited to the first 30 registrants.

I have recently received several turf calls about caterpillars. The majority of the caterpillars are sod webworms and different species of armyworms. I have mostly seen sod webworms, which are less than an inch long and have dark spots over their body. They overwinter as caterpillars in protective webbing. In the spring, they feed and molt into the pupal state.

The adult moths hide in shrubbery or other sheltered spots during the day. They fly over the grass in early evening. The female scatters eggs over the lawns as she flies. Two to three generations occur each year. Sod webworms feed only at night.

Damaged grass blades appear notched on sides and are chewed raggedly. Irregular brown spots are the first signs of damage. Large areas of grass may be damaged severely, especially under drought conditions. A heavy infestation can destroy a lawn in only a few days. Damage tends to become visible in mid to late summer and in highly maintained lawns.

Sod webworms are partial to newly established lawns. Favored turf types are bermuda, centipede, bahia, zoysia and St. Augustine grasses and they tend to survive better in higher-cut turf.

Sod webworm populations (and those of other soil-inhabiting insects) can be monitored using the “irritation technique.” One ounce of dish detergent is mixed with one gallon of water and the solution is poured over a one square yard area where an infestation is suspected. The detergent irritates the insects, causing them to come to the surface quickly.

Damage thresholds vary in different areas. A rough guide is 15 or more larvae per square yard. Insecticide application should be timed for treatment two weeks after peak moth activity and should be made during early evening hours when caterpillars begin feeding.

UGA Extension entomologist Dr. Will Hudson says they have developed an adaptation where if they are sprayed in the latest larval instar, they will go ahead and pupate. In South Georgia, caterpillars can be in issue through September.

What about adult moths? We are still seeing a high amount of moths. It is not recommended to treat moths since most moths do not produce caterpillars that survive to a size that will do noticeable damage. Dr. Hudson says — as of now — it’s pretty late in the season for another generation to do much damage to a healthy lawn.

For more information or questions, contact Effingham Extension agent Sam Ingram at 754-8040 or