Strong south winds earlier this month caused the moths to blow slightly off their regular course and travel through parts of South Dakota.Įach spring, the army cutworm moths migrate west from the Great Plains where the caterpillars were feeding on crops and other vegetation.

Large populations of army cutworm moths are a common occurrence for several states that fall in their normal migration path (i.e., Kansas, Nebraska, Colorado, Wyoming, New Mexico, Arizona). The army cutworm is a migratory insect that travels between the southern Great Plains and the Rocky Mountains each year.

Although there are enough characteristics to see differences between perfectly persevered specimens, many of the samples we were observing had been damaged by the wind or other factors, which made it more difficult to identify the differences. The army cutworm moths are noted for having tan and brown colored wings that have a light colored circle (dot) that is present above a light colored boomerang (Figure 1-B). Western bean cutworm moths are noted for having a light coloration on the edges of the wings with a small light colored circle (dot) that is above a light boomerang shape on each wing (Figure 1-A). So how did we make just a few correct identifications and be wrong on so many others? The reason behind this is the extreme similarity between the two moths.

After revisiting the many photographs that were submitted with reports, we realized that most of the moths were actually army cutworm moths with just a few western bean cutworm moths actually being present. However, when talking with an entomologist from a neighboring state, they suggested the moths could also be army cutworm moths.

Last week, we published an article about the presence of western bean cutworm moths being very abundant throughout Central and Western South Dakota. Courtesy: Adam Sisson, Iowa State University,.

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