Soybean aphids were first discovered in the eastern counties of North Dakota in August of 2001. Since its detection in North Dakota, producers and agricultural professionals have monitored fields for seasonal aphid populations and have applied insecticides when significant infestation warranted treatment to prevent losses. Currently, the recommended threshold is 250 aphids per plant on 80 percent or more of the plants when populations are actively increasing and plants are in the susceptible R1 to R5 growth stage. This threshold provides a seven-day lead-time between scouting and treatment.

Foliar insecticides are the common strategy to control soybean aphids. The use of insecticides...