David Owens, Extension Entomologist, owensd@udel.edu
Congratulations to Chris Leon for correctly identifying last week’s pest as true armyworm. This worm is not often found in soybean, while fall armyworm can get into soybean. Fall armyworm has a black head with a pale Y-shaped suture on the face and 4 small dots arranged in a square pattern on the last abdominal segment. True armyworm has parallel dark lines on a mottled face and pinkish stripes down the side of the body.
So what gives? This field had a lot of grass weeds in it. The adult armyworm moth laid eggs, and larvae stripped the grass in portions of the field. In other portions of the field, the farmer sprayed a herbicide. True armyworm only feed on grasses (such as small grain and corn where they are occasional pests). These caterpillars were wandering, looking for food but not finding any. While extremely abundant in the field, they are slowly starving to death, no need to treat these worms.
