Eastern Tent Caterpillar

The eastern tent caterpillar (Malacosoma americana) is not a significant forest pest in Texas, although it appears annually and can occasionally be found in large numbers.  

The caterpillar primarily targets black cherry, plum, hawthorn, and related species, mostly within the genus Prunus. While attacked trees do not die, repeated defoliation can kill twigs and branches and result in some growth loss. 

Identification 

Eggs are small and dark-colored, laid in masses of up to 300 around a twig. They are covered with a dark glue-like substance that hardens, resembling varnish.  

Mature larvae reach about 2¼ inches in length and are black with brownish markings. They feature a narrow, unbroken white stripe along their back. Pupae are reddish-brown and encased in a tough, paper-like cocoon, which is surrounded by whitish silk mixed with a powdery yellow substance. 

Adult moths have a wingspan of approximately 1½ inches and are reddish-brown in color, with two whitish stripes that run diagonally across their forewings.  

Signs of attack

The first indication of an attack is usually the appearance of silken webbing tents in the fork of branches in early spring. Larvae can often be seen feeding on foliage or resting within the silken tent. 

Life cycle

In late spring, adult insects emerge, marking the beginning of their mating season, after which females lay their eggs on the branches of host plants.  

Eggs hatch in the fall, and the larvae remain within the egg mass until Feb. or March, when they begin feeding on the emerging leaves. These larvae are aggressive feeders and start constructing silken tents almost immediately after hatching, expanding these shelters as they grow.  

The larval stage lasts about six weeks, then pupation occurs, typically inside the remnants of the silken tent. Adults emerge approximately two weeks later. In Texas, this species completes one generation per year. 

Control 

In forest settings, chemical control is not recommended. Natural predators, parasites, and weather conditions help keep populations in check. 

In urban settings, tents containing caterpillars can be manually removed and destroyed. Occasionally, insecticides may be used to protect valuable shade or ornamental trees.  

All suggested chemicals must be currently registered and labeled for use by the U. S. Environmental Protection Agency and the Texas Department of Agriculture. Before using any pesticide, read and carefully follow all application directions, cautionary statements and other information appearing on the label.