This insect has one generation a year. It overwinters as eggs. Eggs hatch in later spring to early summer. Larvae are early-season foliage feeders, feeding on the terminal buds. Spongy moth infestations of cranberry bogs occur mainly through larvae dropping from trees near cranberry beds, but also from eggs overwintering on the bog floor or older larvae crawling onto bogs from surrounding trees.
Spongy moth eggs can successfully survive the winter flood on cranberry beds. Also, first instars “balloon” on silken threads from infested trees onto nearby cranberry beds. Either way, spongy moths tend to be one of the earliest caterpillars to show up in cranberry beds, usually during the first week of May.
They are quite easy to detect by means of sweep net sampling when they are small. Spongy moth larvae are easy to control with most of the insecticides at our disposal: Intrepid, Delegate, Altacor, etc., but also can be quite easily killed by re-flooding infested beds for a day.