Honeylocust pod gall is present in northeastern Illinois. This gall is caused by a midge, a small fly. Affected leaflets round up into podlike structures that are 1/8 to 1/4 inch long. Once galls have formed, control efforts are not effective. This insect is unusual enough in Illinois that preventative treatments are not usually practical.
Four-lined plant bugs are present throughout Illinois on flowers and herbs, particularly mint and oregano. These insects are about 1/4 inch long and yellow with four black stripes. Damage appears as blackish spots and streaks on the foliage.
Black vine weevil damage is occurring throughout the state. Adult beetles eat crescent-shaped notches in the margins of leaves of euonymous, yew, rhododendron, and a wide range of other plants. Larvae live on root systems of yew, strawberry, and other plants. Control involves eliminating adults during the two to three weeks of feeding after emergence before they can lay eggs. With acephate (Orthene), bendiocarb (Dycarb, Turcam), or cyfluthrin (Tempo), spray foliage heavily and allow runoff onto the soil. Larval control is possible from July to mid-October with the insect-attacking nematode, Heterorhabditis bacteriophora used as a soil drench. Containerized stock can be soil-drenched for larval control with carbofuran (Furadan).
(Other contributors to this article: staff at The Morton Arboretum)