Do your trees look like this?
The adult moth lays her eggs on the underside of leaves in 'hair'-covered clusters of a few hundred. Eggs hatch in about a week.
Female moths cannot fly but the larvae can disperse.
Very small caterpillars can spin strands of silk and be carried by wind, an activity called “ballooning”.
Larger larvae may crawl to adjacent plants.
The caterpillars are highly variable in coloration, ranging from a pale yellow to dark grey, with yellow spots and long and short bristles. The webs are progressively enlarged and much messier looking. The webs are concentrated to the tips of the branches. Larvae feed inside the tents with the very young larvae feeding on the upper surfaces of leaves; later, they consume whole leaves.