Bagworms have hatched in southern Illinois and are hatching in central Illinois. This timing is somewhat earlier than normal, as hatch typically occurs in central Illinois in mid-June. Realize that young bagworm larvae balloon from tree to tree on long silk strands for the first 2 to 3 weeks after hatch and that hatching is spread out over a period of a week or more. For these reasons, we do not recommend control until at least 2 weeks after hatch. The amount of damage caused by these young caterpillars is relatively small. Treatment for bagworms in southern Illinois should be delayed until mid-June and in central Illinois until late June or early July.
Periodical cicadas have emerged in the Washington, D.C., area and emerged earlier farther south. Adults should emerge in Vermilion, Clark, and Edgar counties in Illinois, as well as throughout Indiana during the last week of May. You will know when they are out by the song (noise) the males produce, as well as by the brown, nymphal skins on tree trunks. Egg-laying, which causes tree and shrub injury, will not be heavy for at least a couple of weeks. At that time, protect tree trunks less than 1-1/2 inch in diameter with netting or screening that keeps the insects from get-ting to the trunk. This protection should remain in place through mid-July.
Gypsy moth was treated in locations of northern Illinois during the week of May 17. Treatment will continue through the last week of May, possibly into the first week of June. These are applications to con-trol the young larvae. Typically, Bacillus thuringiensis kurstaki is applied by helicopter. Each area is sprayed twice, 1 to 2 weeks apart, to obtain a high level of control or eradication. In late June to early July, some areas will be treated with pheromone flakes to confuse the males, reducing mating and subsequent fertile egg-laying.