The web mass increases in size as larvae increase in size. When mature larvae are about 2 inches long, black, sparsely hairy, with white and blue markings, including a white stripe down the middle of the back. However, most larvae will exit the tent, to spin cocoons under debris on the ground. In two to four weeks, moths emerge, mate and deposit eggs for the next year's spring activities. There is but a single generation per year.
Tent caterpillars are more of a nuisance than actually detrimental to overall tree health and vigor.
As web masses increase in size, they become unsightly. Tent caterpillars often go undetected until their tent becomes of sufficient size to be noticed. By this time, larvae will have essentially completed their development. So they might as well be ignored. However, if a web mass is deemed objectionable, it may be easily removed by using your hands.