Tents that are the size of baseballs are now visible on wild cherry trees in south central Kentucky. Early tents appear near egg masses and caterpillars will feed there for a time. As they grow, caterpillars leave their small, scattered nests on trees in order to form a few large clusters and webbing at major branch angles (Figure 1). It is much easier to manage tent caterpillars while they are still clustering in their protective tents.
Tents and feeding damage can be unsightly, so some form of management may be needed.
- When practical, tents can be clipped and destroyed. Be sure to do this when the caterpillars are ‘at home’ rather than when most are out feeding.
- Insecticide sprays are an option. The hairy bodies of the caterpillars pose a challenge for contact insecticides. The best strategy could be to treat foliage around tents with insecticides containing Bt or spinosad as active ingredients. These insecticides are selective and should have limited impact on beneficial insects.
After feeding for about 6 weeks, caterpillars leave their trees and wander to find pupation sites. When tent caterpillar populations are high, this can mean thousands of worms crawling across landscapes. Control options at this point are generally ineffective. It is important to identify intensely infested trees early and reduce caterpillar numbers as much as possible before the advantage of their social structure is lost.
By Lee Townsend, Extension Entomologist