Eastern tent caterpillars, common native insects, are often recognized by the distinctive silk tents they construct in tree branches during spring. These creatures undergo a complete transformation, a process known as metamorphosis. This journey changes their form, leading them from a leaf-eating caterpillar to a winged adult.
The Cocoon and Pupal Stage
Once eastern tent caterpillars reach their full size, typically around 2 to 2.5 inches long, they leave their silk tents and disperse. Each caterpillar seeks a sheltered location to begin its next stage. They then construct a cocoon, a protective casing for transformation.
The cocoon is composed of white or yellowish silk, often dense and mixed with a powdery yellow substance. Inside the cocoon, the caterpillar transforms into a pupa, the inactive, intermediate stage of metamorphosis. The pupal case is typically brown, and the insect undergoes cellular reorganization. This pupation process lasts two to four weeks.
Emergence of the Adult Moth
The adult eastern tent caterpillar moth emerges from the cocoon, completing its metamorphosis. These moths are medium-sized, with a wingspan of 0.75 to 1.75 inches. They are reddish-brown, with two pale or cream-colored diagonal stripes across their forewings.
Moths are furry, with thick scales on their bodies and feathery antennae. Female moths are often paler, more yellowish, and typically larger than males. The adult moth’s purpose is reproduction; it has a short lifespan and does not feed. Its brief existence is dedicated to mating and laying eggs.
The Full Life Cycle
The eastern tent caterpillar life cycle begins in late spring or early summer when the adult female moth lays a single mass of 150 to 400 eggs. These eggs are deposited in a foamy, varnish-like substance that encircles small twigs and remain there throughout the winter. In early spring, in March or April, the eggs hatch, coinciding with the emergence of new leaves on host trees.
Newly hatched caterpillars are gregarious, living and feeding in groups. They immediately construct and enlarge their silk tents in tree branch crotches. They feed on tree foliage for four to six weeks, growing considerably during this larval stage. Once fully grown, in late spring or early summer, the caterpillars leave their tents to find locations for pupation. After two to four weeks in their cocoons, the adult moths emerge, ready to mate and lay eggs, completing the cycle. This species has only one generation per year.