May. Females lay eggs in band-like masses on small twigs. Embryos develop to first-stage larvae within about three weeks. Larvae enter diapause and remain dormant within egg shells through summer, fall, and most of winter. Hatch usually occurs during late February and early March, corresponding to time of start of leaf development. Caterpillars construct webs and feed for about six weeks, with larval development being over in most years by the end of April.
Adults emerge within about three weeks to begin a new cycle.
There is only one brood each year. Infestations occur throughout the countryside, but the caterpillar is most serious as a pest in urban, suburban, and wooded outdoor recreational areas. Here, unsightly webs and leafless crowns severely reduce the aesthetic and environmental values of shade, ornamental, and other landscape trees, and caterpillars, simply by their presence, often become a nuisance. Control of the eastern tent caterpillar is not usually necessary, but may sometimes be desirable in urban, suburban, or recreational areas. If needed, recommendations for control can be obtained from the County Extension Office.