Imported longhorned weevil

The weevils are found on soybean in late June to early July, when they feed on leaf tissue and smaller veins. Their feeding causes a ragged, scalloped leaf border and tends to be found mainly on field margins. The adult weevils are small, mottled gray in color and do not fly.

Imported longhorned weevil - Soybean Insects Guide, Iowa State University

Japanese beetle

Japanese beetles are found in the more southern areas of the region. They are easy to identify with their metallic green and copper-coloring, about 3/4 inch in length. They feed mid-June through August.

Japanese beetles can be voracious feeders but tend to congregate in certain areas. Be sure to scout the entire field to determine the extent of the damage.

Japanese Beetle - Illinois Extension IPM

Seedcorn maggot

The seedcorn maggot are soil-inhabiting, yellow larvae about 1/4 inch long. They feed on newly planted soybean seed. The adult flies prefer to lay their eggs in fields containing freshly decaying organic matter. Damage is most likely to occur during a cool, wet spring when seed germination is slow.

Seedcorn maggot - Great Plains IPM Guide

Soybean looper

The soybean looper is a caterpillar about 1 1/4 inches long that moves with the characteristic looping movement. It is a sporatic feeder on soybeans, usually found mid-July to mid-August. The larvae eat leaf tissue, leaving irregularly-shaped holes between the veins.

Soybean looper - Soybean Insect Guide, Iowa State University

Thistle caterpillar

Thistle caterpillars are bristly, black and yellow larvae of the painted lady butterfly. They feed on soybeans in July and August, causing minor defoliation. The second generation will feed on the top layer of leaves and will web the leaves together with silk.


Thistle caterpillar - North Dakota State University

Whitefly

Whiteflies are tiny white flies and powdery wings that are common pests of greenhouse plants. They are minor pests on soybeans that can be confused with soybean aphids. Be sure you can distinguish between the two insects.


White fly on Iowa soybeans - Iowa State University