Soybeans Insects

Corn Earworm (Heliothis zea)

Both the corn earworm and tobacco budworm, H. virescens, occur on soybeans but the corn earworm is by far the predominant species. Both species do the same type damage. The corn earworm is a robust, aggressive caterpillar about 1 1/2 inches long (38 mm) when mature. It varies greatly in color but the head capsule is large and usually yellowish-orange. There are 4 pairs of abdominal prolegs. The corn earworm will feed on leaves and blooms but it is primarily a pod-feeder. It chews holes into the side of the pod and eats the beans inside.

Corn earworm and damage to soybean pod

Loopers:
Soybean Looper (Pseudoplusia includens)
Cabbage Looper (Trichoplusia ni)

The soybean looper is the predominant looper found on soybeans but cabbage looper infestations may occasionally be found. The larvae of both species are greenish, tapered from the rear to the head, about I 1/2 inches long (38 mm), and crawl with a looping motion. They have 2 pairs of abdominal prolegs. The soybean looper usually has black thoracic legs and small black spots on the body, whereas the cabbage looper does not. Both hatch from eggs laid singly on the plant parts and chew ragged holes in the plant foliage. Pupation occurs on the undersides of leaves in flimsy silken webs.

Soybean looper and typical damage to soybean leaf

Velvetbean Caterpillar (Anticarsia gemmatalis)

The velvetbean caterpillar is a long, slender, green to black larva that usually has white stripes down the body,and is about 11/2 inches long (38 mm). It has four pairs of abdominal prolegs. Velvetbean caterpillars usually have a long globular head capsule which is usually yellowish-orange. When disturbed it will flip about very rapidly. After plants are stripped of leaves, larvae may feed on the pods and stems.

Velvet caterpillar and defoliated soybean plant

Stink Bugs:
Southern Green Stink Bug (Nezara viriduIa)
Green Stink Bug (Acrosternum hilare)
Brown Stink Bug (Euschistus servus)

The southern green stink bug, green stink bug and brown stink bug are shield shaped, and about 1/2 to 5/8 inch long (13-15 mm). The triangle between the wings (scutellum) is about 1/2 the length of the wing. They hatch from relatively large, barrel-shaped eggs which are laid in groups on plant foliage and all damage soybeans in the same manner. These insects have piercing-sucking mouthparts with which they

Southern green stink bug on soybean pod

Typical stink bug damage to soybeans

Brown stink bug on soybean pod

Mexican Bean Beetle (EpiIachna varivestis)

The adult Mexican bean beetle is coppery-brown in color with 16 small black dots on its back. It is about 1/4 inch long (6 mm) and lays its oblong, yellow eggs in clusters on the leaves. The larva is bright yellow and covered with branched spines. Larva and adults feed primarily on the undersides of the leaves and damaged leaves are left with a lacy," silver-brown appearance. All stages of the insect can usually be found on infested plants.

Eggs, larva, pupa and adult Mexican bean beetle

Green Cloverworm (Plathvpena scabra)

Green cloverworm larvae are green in color, are usually striped and about 1 1/4 inch long (3. I cm). They have 3 pairs of abdominal prolegs. They feed almost entirely on the leaves.

Green cloverworm on soybean leaf

Beet Armyworm (Spodoptera exigua)

Eggs are deposited on plant foliage in small, fuzzy masses. Larvae are pale green to blackish-green, about 1 1/4 inches long (31 mm), and with a black dot on each side of the thorax just above the second pair of thoracic legs. The larva has 4 pairs of abdominal prolegs. When first hatched, and until they are about 1/2 inch long(13 mm), they feed on the leaves in groups and often web the leaves together.

Beet armyworm on soybean leaf

Lesser Cornstalk Borer (Elasmopalpus lignosellus)

The lesser cornstalk borer is relatively small, up to about 3/4 inch long (18 mm), bluish-green or reddish brown in color with dark bands around the body. It will "whip about" violently when disturbed. It attaches a soil-covered, silken tube to the plant just below the soil level and from this tube tunnels into the stem. Seedlings may be killed or damaged to the point that they will lodge later in the season. Damage is most common on sandy soils following periods of drought.

Lesser cornstalk borer and damaged soybean seedlings

Bean Leaf Beetle (Cerotoma trifurcata)

The bean leaf beetle is relatively small, about 3/16 inch long (4.6 mm) and is variable in color, usually being green, yellow, orange or red. There are usually 6 black spots on the wing covers. Some color phases have but two small black spots at the tip of the wing covers. This beetle damages soybeans primarily by feeding on the leaves but will sometimes rasp on the outside of the pods.

Bean leaf beetle on soybean leaf

Fall Armyworm (Spodoptera frugiperda)

The female moths lay clusters of about ISO whitish eggs, usually on the undersides of leaves. The egg masses are covered with fine scales from the female moth. Larvae vary in color from tan or green to nearly black, are about I 1/2 inches long (38 mm). and have several stripes on the sides and/or the back which run the length of the body. The fall armyworm will usually have an obvious inverted white ~Y" on the front of the dark head capsule. Larvae may feed on leaves, blooms or pods. Most damage occurs when they eat the beans out of the pod.

Fall armyworm damaging soybean pods

Three-cornered Alfalfa Hopper (Spissistilus festinus)

The three-cornered alfalfa hopper is a green or yellowish-green wedge shaped insect, and about 1/5 inch (5 mm) long. Adults have 2 pairs of membranous wings partially concealed beneath a hard projection arising from the front of the insect and extending backwards. Nymphs have spiny projections arising over the body. Both adults and nymphs have piercing-sucking mouthparts. They suck juices from the developing main stem near the soil line. Seedlings may be girdled and die or damaged plants may survive but lodge later in the season. These insects can be found on soybeans throughout the season but damage is mostly on beans less than 12 inches (30 cm) tall.

Threecornered alfalfa hopper on soybean stem