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Wandering Eastern Tent Caterpillars

Cliff Sadof
Department of Entomology

Ever wonder about why caterpillars wander? Well, owing to recent outbreaks of EASTERN TENT CATERPILLARS in Southern Indiana, this is a burning question for many homeowners this year.

Eastern tent caterpillars are normally found during the day in cozy little webs located in the central crotches of trees. At night they move to the tree-tops to feed on leaves. This insect is most common on flowering fruit trees. They start feeding in early April, just as the leaves began to unfold. Normally they are easily controlled by either mechanically removing the web and killing soaking the caterpillars in soapy water, or by spraying with a Bacillus thuringiensis (Thuricide) or carbaryl (Sevin). While their damage rarely if ever affects tree health, the presence of thousands of 2-inch long caterpillars has given more than one homeowner a terrific fright. Moreover, like most other caterpillars, when they finish growing, they stop eating and begin to search around for a safe place where they can make their cocoons and transform into a night flying moth.

That's right. Wandering caterpillars do not eat much if at all. As such, there is no real pressing need to control them from the standpoint of protecting trees. On the other hand, the prospect of sharing your yard with thousands of caterpillars is no picnic either. Fortunately this phenomenon does not last very long. In about a week, most of the caterpillars will already be tucked away in their cocoons, never to been seen from again until the following spring. Waiting a week until this mess blows over is probably the best strategy.

Now, individuals who are unlucky enough to have this wiggly extravaganza coincide with the annual family barbecue may not want to share their patios with these furry little freeloaders. A non-pesticidal option would be to use a hard stream of water to hose and corral the caterpillars into a heap that can be shoveled into a bucket of soapy water. Alternatively, an insecticide can be applied to kill the caterpillars. Effective materials, labeled for homeowners should have one of the following active ingredients, bifenthrin, cyfluthrin, diazinon, malathion, pyrethrin, and resmethrin. To prevent the offensive odor associated with the decay of large numbers of caterpillars, homeowners should be sure to sweep up the dead insects and toss them into the compost or a trash bin.

For photos of Eastern Tent Caterpillar please refer to the following web address http://www.entm.purdue.edu/Entomology/research/cs/notes/307E/lab7/7.1.html (be sure to double click on images for larger views)

The information given herein is supplied with the understanding that no discrimination is intended and no endorsement by the Purdue University Cooperative Extension Service is implied. Any person using products listed assumes full responsibility for their use in accordance with current direction of the manufacturer. Purdue University is an equal opportunity/equal access institution.

Information listed is valid only for the state of Indiana.

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