Title

Common Arthropod Pests of Soybeans in North Dakota

(E2005, Reviewed March 2025)
Summary

This publication describes the common arthropod pests of soybean in North Dakota. The following pests are included: foliage-feeding caterpillars (green cloverworm, painted lady butterfly), potato leafhoppers, soybean aphids, spider mites, armyworms, bean leaf beetles and cutworms. To help pest managers with proper identification, a brief description and photograph of the immature and adult life stages is provided for each pest.

Lead Author
Lead Author:
Janet J. Knodel, Professor and Extension Entomologist
Other Authors

Patrick B. Beauzay, IPM Coordinator and Research Specialist

Availability
Availability:
Available in print from the NDSU Distribution Center.

Contact your county NDSU Extension office to request a printed copy.
NDSU staff can order copies online (login required).

Publication Sections

Foliage Feeding Caterpillars

Green Cloverworm

Caterpillar (larva, Figure 1): Mature larva about 1¼ inches long. Pale green, with one long narrow white stripe on each side, three pairs of fleshy prolegs at the center part of the body and one pair of prolegs at the rear end. Moves in a looping behavior. Chew on leaves and pods.

Figure 1. Larva - green cloverworm
Photo Credit:
J. Gavloski, Manitoba Agriculture, Food and Rural Initiatives
Figure 1. Larva - green cloverworm

Adult (Figure 2): Wingspan of 1 inch. Dark brown moth with spots. When moth rests, wings form a triangle. Migrates into North Dakota each spring.

Figure 2. Green cloverworm moth
Photo Credit:
J. Gavloski, Manitoba Agriculture, Food and Rural Initiatives
Figure 2. Green cloverworm moth

Painted Lady Butterfly

Thistle Caterpillar (larva, Figure 3): Mature larva about 1½ inches long. Brown to black with yellow striping along each side of the body and covered with branched spiny hairs (giving a prickly appearance). Webbed nest in curled leaves where they feed on foliage. Black pellets (frass) inside web.

Figure 3. Thistle caterpillar in webbed nest
Photo Credit:
V. Calles-Torrez, NDSU
Figure 3. Thistle caterpillar
in webbed nest

Adult (Figure 4): Wing span of 2½ to 3½ inches. Forewings red-orange and brown with black and white spots. Hindwings orange-brown with four black “eye spots” along edge. Feeds on flower nectar and aphid honeydew. Migrates into North Dakota each spring.

Figure 4. Painted lady butterfly
Photo Credit:
P. Beauzay, NDSU)
Figure 4. Painted lady butterfly

Soybean Aphid

Nymph (Figure 5): Similar to adult, but smaller and wingless.

Figure 5. Soybean aphid nymphs and adults on underside of leaf
Photo Credit:
P. Beauzay, NDSU
Figure 5. Soybean aphid nymphs and adults on underside of leaf

Adult (Figure 6): Small, about 1/16 inch long, light yellowish-green pear-shaped body, black cornicles (look like tailpipes on posterior end), either winged or wingless.

Figure 6. Adult - soybean aphid
Photo Credit:
P. Beauzay, NDSU
Figure 6. Adult - soybean aphid

Both nymphs and adults feed on plant juices.

Spider Mite

Immature: Similar to adult, but smaller with six to eight legs.

Adult (Figure 7): Small, less than 0.02 inch (magnification is needed to see them in detail), green, yellow or orange body, two dark spots on the abdomen for two-spotted spider mite, eight legs. Located on the undersides of leaves. Produce spiderlike webbing (Figure 8) and stippling injury on leaves (Figure 9).

Figure 7. Two-spotted spider mite
Photo Credit:
D. Cappaert, Michigan State University, Bugwood.org
Figure 7. Two-spotted spider mite
Figure 8. Webbing from two-spotted spider mites
Photo Credit:
D. Cappaert, Michigan State University, Bugwood.org
Figure 8. Webbing from two-spotted
spider mites
Figure 9. Stippling injury from twospotted spider mites
Photo Credit:
W. Cranshaw, Colorado State University, Bugwood.org
Figure 9. Stippling injury from twospotted spider mites

Armyworm

Larva (Figure 10): Light tan to dark greenish-brown caterpillar with three longitudinal stripes (pale orange, white, brownish or/and black) on smooth and almost hairless body, about 1½ to 2 inches long when mature. Defoliate leaves/pods, usually in moist, shady areas with lodged plants.

Figure 10. Larva - armyworm
Photo Credit:
P. Beauzay, NDSU
Figure 10. Larva - armyworm

Adult (Figure 11): Light brown moth with a conspicuous white spot about the size of a pinhead on each front wing, wingspan of 1½ inches.

Figure 11. Adult - armyworm
Photo Credit:
G. Fauske, NDSU
Figure 11. Adult - armyworm

Cutworm

Larva (Figure 12): Black to pale gray body with markings (spots or stripes), 1½ inches long when mature. Cut young plants below or above ground.

Figure 12. Larva - dingy cutworm larva
Photo Credit:
J. Gavloski, Manitoba Agriculture, Food and Rural Initiatives
Figure 12. Larva - dingy cutworm larva

Adult (Figure 13): Dark gray, brown or dull yellow or tan moths with dark wing markings, robust body, wingspan length of 1¼ to 1½ inches.

Figure 13. Adult - dingy cutworm
Photo Credit:
G. Fauske, NDSU
Figure 13. Adult - dingy cutworm

Bean Leaf Beetle

Larva: White body with a brown head, about ¼ inch long when mature. Found in soil, feeds on roots, root hairs and nodules.

Adult (Figures 14 and 15): About ¼ inch long, oval-shaped, greenish-yellow to reddish-brown beetle, with four black spots on wings (spots also can be absent) and black margin near wing edges. Beetle always has a black triangular mark in middle and behind prothorax. Adults feed on foliage causing small, round holes between leaflet veins and on pods (Figure 16).

Figure 14. Adult - yellow bean leaf beetle
Photo Credit:
J. Kalisch, Nebraska State University
Figure 14. Adult - yellow bean leaf beetle
Figure 15. Adult - red bean leaf beetle
Photo Credit:
J. Kalisch, Nebraska State University
Figure 15. Adult - red bean leaf beetle
Figure 16. Bean leaf beetle defoliation and pod damage
Photo Credit:
J. Kalisch, Nebraska State University
Figure 16. Bean leaf beetle defoliation and pod damage

Potato Leafhopper

Nymph (Figure 17): Similar to adult, but smaller, wingless and greenish yellow.

Figure 17. Nymph - potato leafhopper
Photo Credit:
S. Brown, University of Georgia, Bugwood.org
Figure 17. Nymph - potato leafhopper

Adult (Figure 18): Less than 1/8 inch long, narrow, wedge-shaped, pale green body. Wings are transparent green and folded over back at rest. Nymphs and adults jump or walk rapidly sideways when disturbed. Migrates into North Dakota each spring.

Figure 18. Adult - potato leafhopper
Photo Credit:
S. Brown, University of Georgia, Bugwood.org
Figure 18. Adult - potato leafhopper

Both nymphs and adults feed on plant juices.

Published with supported from the North Dakota Soybean Council, the North Dakota Department of Agriculture, the USDA National Institute of Food and Agriculture, Hatch Project Accession No. 1018411 and the Crop Protection and Pest Management - Extension Implementation Program [award number 2024-70006-43752].

This publication was authored by Janet J. Knodel, Professor and Extension Entomologist and Veronica Calles Torrez, Former Post-doctoral Scientist, 2020.

For more information on this and other topics, see www.ndsu.edu/extension

County commissions, North Dakota State University and U.S. Department of Agriculture cooperating. NDSU does not discriminate in its programs and activities on the basis of age, color, gender expression/identity, genetic information, marital status, national origin, participation in lawful off-campus activity, physical or mental disability, pregnancy, public assistance status, race, religion, sex, sexual orientation, spousal relationship to current employee, or veteran status, as applicable. Direct inquiries to Vice Provost for Title IX/ADA Coordinator, Old Main 201, NDSU Main Campus, 701-231-7708, ndsu.eoaa@ndsu.edu. This publication will be made available in alternative formats for people with disabilities upon request, 701-231-7881. 2.164M-12-20