06/06/2026
If you look at a black cherry tree (Prunus serotina), you may notice web-like structures typically located where the branches form joints (also referred to as branch crotches). However, these structures are not the workings of a spider but rather an insect during its larval stage. That insect will one day become a moth but the structure is a result of eastern tent caterpillar activity.
Come spring time, eastern tent caterpillars emerge from an egg mass located on a branch of a host tree which is typically a type of cherry or crabapple. With the objective of increasing its size several times over, the eastern tent caterpillar will immediately begin to consume the foliage of the tree. Using silk as a construction material, a tent structure is built where the caterpillars will congregate. As the caterpillars increase in size, they will add layers to their tent to accommodate their growth. The tent also allows for temperature regulation which is an important part of the digestive process and moisture regulation which can help with several molts the caterpillar will go through prior to pupation.
As summer approaches, the eastern tent caterpillar will form a cocoon where it will pupate. After a period of about 2 weeks, it will enter its final life stage as it exits the cocoon as a moth.
As a moth, it is mainly nocturnal and short-lived with its adult life spent mating and, if it is a female, depositing a mass of eggs around the twig of a host tree branch. The eggs will remain dormant until the following spring season where the life cycle will begin anew.
Both the caterpillars and the moths provide invaluable food sources for migratory birds and other animals in the food web.
Photos: NPS / T. Ozerol
