Eastern tent caterpillar (ETC) egg hatch was reported March 23 in Scott County by Larry Hanks, a consulting arborist. The tiny larvae will continue to emerge over the next 2 weeks from eggs (Figure 1) laid last summer on wild cherry flowering, cherry, apples, and related trees. This is a hardy insect, so it is unlikely that our winter temperatures caused much mortality.
Populations of ETC have been climbing over the past few years. This trend is likely to continue, producing locally high numbers in some areas.
When mature, large, hairy caterpillars wander from their developmental sites along fence lines. Consumption of large numbers of caterpillars by pregnant mares precipitated foal losses in Mare Reproductive Loss Syndrome (MRLS) outbreak of 1999-2001. Horse owners/farm managers with pregnant mares should begin to monitor fence lines containing wild cherry trees in about 2 weeks. Look for small tents produced by developing caterpillars. ETC are also a significant nuisance to people living near heavily infested trees. The caterpillars may wander hundreds of yards in search of protected sites to spin cocoons and pupate.
The UK Entomology publication, Checking Eastern Tent Caterpillar Egg Masses (ENTfact 449), can be used when assessing trees for egg masses.
By Lee Townsend, Extension Entomologist