Soybean Aphids Making Their Summer Appearance Early

 

Two small, soft-bodied insects have begun showing up in South Dakota soybean. One is the soybean aphid, and the other is a mealybug.

 

 

 

 

 

Soybean aphids are yellow to yellow/green and are usually found feeding on the underside of leaves (Figure 1). The incidence of soybean aphid has been a bit higher than typical for this time of year (mid-June). This doesn’t necessarily mean a terrible summer for aphids, but it does mean that producers should start their scouting early, paying particular attention to locations with a history of problems. The recommended threshold is still 250 aphids/plant, even for early-season populations. More information about soybean aphid management can be found in the Soybean Aphid Scouting and Management article on iGrow.

 

 

Mealybugs in June soybeans can sometimes be confused with aphids. They are small insects with a waxy white covering that are typically found on the roots and the lower stems and leaves of soybean plants during June in South Dakota (Figure 2). They are similar in size to soybean aphids and also remove plant sap with piercing-sucking mouthparts. In past years, infestations have been light and have dissipated with the onset of warmer, drier weather. Mealybug infestations have not been economically important in South Dakota, but eastern soybean-producing states have occasionally had significant mealybug populations on roots of yellowing soybean plants.