We continue to receive calls on the large number of adult moths in much of Illinois. They congregate on plants in bloom, including linden and spiraea. The moths appear to be adults of armyworm and/or black cutworm.
Armyworm adult moths are 1 inch long, with tan to gray-brown wings. Each front wing has a single white dot near the center. Black cutworm adult moths are 1 inch long, with a 2-inch wingspan. The front wings are mottled, with medium to dark-brown coloration. The hind wings are light-colored.
These insects most likely migrated from the South, from where (due to our unusual warm weather in early spring) they were carried northward on wind currents originating in the Gulf of Mexico.
The adults may be a nuisance and find their way into homes; however, they do not harm people or plants. The adult female moths will eventually lay eggs, which will hatch in caterpillars that, depending on their numbers, may damage turf or landscape plants. Be on the lookout for the caterpillars in 1 to 2 weeks, depending on the temperature. It is important to understand that high moth numbers do not directly translate into high caterpillar numbers. As a result, avoid making any preventive insecticide applications.