Cottony Ash Psyllid Facts

Eggs laid in the trees, hatch in spring and the nymphs (immature insects) start feeding on the growing leaves. At this stage, when feeding on new leaves, they suck out the sap causing the leaves to curl, and produce a white cottony substance.

Around July, these same nymphs become adults and lay eggs which will hatch in August. The second generation nymphs feed in the curled leaves that were created by the first generation. The white cottony substance actually provides them with a measure of protection from any spray applications.