Mimosa webworm damage is heavy on honey locust throughout the state and on silk tree or mimosa in southern Illinois. The second generation of this insect webs several compound leaves together and then window-feeds on the leaves, causing the leaves to turn brown. This damage is very obvious when the webworm is numerous, as it is this year.
Many of the webs are empty of caterpillars and most of the damage has been done. Next summer, be watchful of trees next to buildings, where the larvae will find warmer overwintering sites along foundations and under siding. Those trees are most likely to be attacked heavily next year if we have a normal to severe winter. If we have a mild winter again this year, this insect will probably be numerous on any host trees, regardless of site. The first generation of mimosa webworm usually appears in June.