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Cutworms Gone Wild

Jeffrey Hahn, Asst. Extension Entomologist

Many parts of Minnesota experienced large numbers of adult cutworm moths recently. However, it was not so much the moths that were noticed as were the many eggs that were laid on homes on windows, siding, soffits and other places. Clusters of eggs were reported from the Twin Cities up to northern Minnesota, especially in the northeastern part of the state. Some towns found that essentially all buildings had at least some eggs on them. One resident said he found as many 15 clusters of eggs on his home. Wisconsin also experienced a similar phenomenon with cutworm eggs found in much of the northern half of their state.
Insect eggs are often challenging to identify, especially to species. While it was fairly easy to diagnose the eggs as belonging to a moth, it wasn't until someone was finally able to catch the culprit in the act of laying eggs that the species could be identified as a variegated cutworm. Variegated cutworms are native to Minnesota but it is very unusual to see such large numbers, especially in northern Minnesota where they are rarely seen.

Mike Misk

Photo 1: Variegated cutworm eggs on house

An individual variegated cutworm egg is tiny, about 1/50th in diameter. It is hemispherical with many ridges and is whitish or yellowish at first, before turning brown. There can be hundreds of eggs in a single cluster. Once they hatch, they are small and dark. As they grow larger, they are brownish to black with four to five yellowish diamond-shaped spots on the top of the body starting at the head. You may also see a dark-colored 'W' on top of its body near the posterior. They can be up to two inches long when fully grown.

You might expect that with so many eggs being laid that this would mean an increased problem with cutworms in gardens and agricultural fields. So far this has not been the case. Still, if you noticed clusters of eggs in your area, monitor your garden and watch for signs of cutworms, i.e. young plants cut off at ground level. The eggs laid on homes are little risk to gardens, as the caterpillars are very likely to die before they can move and find susceptible plants.  Click here for more information on cutworms, including management.
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