Wheat head armyworms are becoming more common, and thus more conspicuous, throughout north central and south central Kansas. This insect is only a very minor pest most years, but there are always a few (<1%) infesting most wheat fields.
They are not usually a problem; however, occasionally populations can occur to such an extent as to cause some damage to kernels in the field. Sometimes their feeding on the kernels may even result in wheat being downgraded by the buyers because of what they refer to as “insect-damaged kernels” (IDK).
Some of the fields sampled this week had numbers of these larvae that are a little higher than usual. The typical feeding position of these larvae is seen in photos 2 and 3 below, where they are feeding directly on the grain.
These pests are not common enough to have caused us to develop any kind of management or control recommendations. They also occur late enough relative to the development of the wheat that insecticide applications would be rather “iffy” and the post-harvest interval (PHI) of any insecticide selected would need to be carefully monitored to ensure label compliance.
Figure 1. Wheat head armyworm larva. Photos by Holly Davis-Schwarting, K-State Research and Extension.
Figure 2. Wheat head armyworm on wheat awn.
Figure 3. Closeup of wheat head armyworm on head of wheat.
Jeff Whitworth, Extension Entomologist
Holly Davis-Schwarting, Entomology Insect Diagnostician