Beetles And Bugs And Worms! Oh, My!

Don’t let insects invade your field this growing season

I’ll get you, my pretty, and your little field, too!

From beetles to bugs to worms, there’s a variety of pests that could impact your yield. It’s important to scout for pests during the correct soybean growth stages. If you find an insect in your field, have no fear. Below are guidelines to help you identify the proper treatment threshold to ensure you get the most out of your investment.

Thresholds vary by region. For best results, be sure to check out your local extension for the most accurate thresholds for your area.

Bean Leaf Beetle

Scout soybeans in the stages R1-R3 and R5-R7. Consider treatment in the early stages (R1-3), if defoliation reaches 20-25 percent and a large number of bean leaf beetle adults are present. If pod injury is above 10 percent and beetles exceed three per sweep in the late-pod stages (R5-R7), consider treatment, especially if other pod-feeding insects, such as grasshoppers and caterpillars, are present.

Fall Armyworm

Scout soybeans after full bloom, when pods are forming. Treatment is based on the size of the caterpillar and level of infestation. Check 20 consecutive plants in five different areas of your field to determine plant damage. Young worms may feed on the stem or leaves. Also, look for discolored, wilted or dead plants. Consider a treatment if larvae are less than three-quarters of an inch long and more than 20 percent of plants are damaged or missing.

Green Cloverworm

Scout soybeans from stages V1 to R7. Consider treatment if defoliation is greater than 40 percent during the pre-bloom stage and 15 percent from stages R1-R5. For stages R6 to harvest, consider treatment if the threshold is greater than 25 percent defoliation and larvae are actively feeding. Before applying treatment, determine the condition of larvae as green cloverworms are very susceptible to parasites and diseases, so they may not reach damaging levels.

Kudzu Bug

Scout fields in the R2-R3 stages when nymphs typically appear, using a sweep net. Infestations typically appear heaviest along the edges of a field. If adults are present and there is one nymph per sweep, consider treatment.

Soybean Aphid

Scout fields in stages V2-R6, from June until August. Check 20 to 30 plants throughout the entire field focusing on looking at the undersides of leaves. The threshold should reach 250 aphids per plant to justify treatment. Additionally, look for ants on soybean stems and leaves. The presence of ants on soybean plants might be an indicator of soybean aphids because as they feed, aphids release a sugary sap that attracts ants.

Soybean Looper

Scout soybeans from stages R1 to R8. The threshold for the soybean looper is 30 percent defoliation throughout the plant two weeks prior to blooming (R1), and 15 percent defoliation two weeks prior to blooming until the pods have filled (R7-R8). Soybean plants are relatively tolerant of early season defoliation. However, a treatment may be justified if more than 35 percent defoliation was estimated in a field.

Brown Marmorated Stink Bug

Scout soybeans throughout the season, particularly from stages R2 until mid-August, paying special attention to the field edges. The threshold is 2.5 to 3.5 brown marmorated stink bugs for every 15 sweeps. Populations will be highest at dusk and dawn, and reinvasion is possible after treatment.