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April 25, 2003

Eastern Tent Caterpillar Update

Lee Townsend, Extension Entomologist
Department of Entomology
University of Kentucky College of Agriculture

Tent caterpillars can be found in a wide range of sizes now as shown in the pictures taken on April 24. Caterpillars in a small number of tents are about 1 inch long but those in many tents are close to 1.5 inches. There can be a wide range in individual size within tents that harbor large caterpillars. Also, defoliation is becoming more noticeable as caterpillar feeding increases. ETC infestations on small trees may be great enough to force them to move to nearby trees to get enough food to complete their development.

Behavior changes as caterpillars near maturity. Individuals become more independent, will lose their strong ties to the colony, and will feed at night as well as during the day. They are less likely to return to the tent and can begin to rest more on larger branches or the main trunk or over a wider area of the tree line. This impacts late control efforts because the larvae are scattered over a larger area of the tree.

The great variation in caterpillar development is not unusual but it does spread out the timetable for the population. Some of the largest caterpillars should be leaving trees to find pupation sites in about a week but others will not reach this stage for some time. Since there are no good control alternatives for wandering larvae, it is best to focus management on aggregated caterpillars.

Credits: Beth Ann Choate, UK Entomology Graduate Student, and Drs. L. Rieske, D. Potter, and K. Haynes have provided information in the update provided this spring. R. Hillard took the pictures.




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