Flights of soybean aphids have landed in farm fields in northwest and east central Missouri creating havoc on soybean crops. Other locations may not be safe.
The tiny pests, which stunt soybeans by sucking the plants' fluids, can build large populations in a few days. "Soybean producers should be scouting their fields for the pest every couple of days," says Wayne Bailey, University of Missouri Extension entomologist.
"Cool nights have encouraged the invasion," Bailey says. When huge populations build up in a field, female aphids develop wings and fly upward. Once airborne, the insects can be blown hundreds of miles before dropping out of the sky.
First reports came from Gentry County, northeast of St. Joseph, and from Pike County, south of Hannibal.
Bruce Burdick, superintendent of the MU Hundley-Whaley Farm at Albany, says his soybean research plots have large populations of the tiny greenish-yellow aphids. "We'll have to spray." Burdick has also found aphid infestations in fields in Gentry and Worth counties. "Every field I've been in had populations near or above the threshold for economic damage."
Bailey says farmers should consider spraying a field once insect counts reach over 250 aphids per plant. Farmers looking for the pests should part the leaves and look up and down the plants. A hand lens of 10X magnification power is needed to identify an individual aphid. However, in mass, aphid colonies can be highly visible.
There is good news, Bailey adds. Large populations of ladybug beetles, natural predators of aphids, already live in the soybean fields. There also are other natural enemies of the aphids, which help control the infestations.