The May 16th bulletin from Ontario Ministry of Food and Agriculture (OMAFRA) warns that Eastern Tent Caterpillars have hatched and the tiny, black fuzzy larvae can be seen inside webby tents found in tree branch crotches. To destroy the larvae, remove and destroy the tents during daylight hours in the first week or two after their appearance. Since the young larvae come out of their tents to feed at night, apply the biological insecticide B.t on the foliage during the evening . Larvae will turn black and die approximately 3-5 days after eating the B.t. residue on the foliage.
Gypsy Moth eggs are hatching, too. B.t. can be helpful to control their larvae also. You can install a burlap skirt at the base of the tree to create a shady, protected area for larvae to hide during the day. Every day, inspect the burlap skirts and underlying bark crevices in early afternoon and remove/destroy larvae. Sticky bands around trunks during the June/July flight period will help prevent females from laying eggs above the bands and will attract males to the sticky surface.