Adult Japanese beetles first emerged in some areas of Iowa around the end of May. This is very early compared to a normal year. At the same time, many other beetles in this large insect family (Scarabaeidae) are becoming active and causing confusion with identification. In general, scarabs are stout beetles that are boxy in shape, have clubbed antennae and thick legs adapted for digging. Adults can be active during the night or day depending on the species; regardless, they are clumsy fliers. Some species are scavengers that feed on dung, carrion or decomposing organic materials; others can be significant plant pests. In most years, adult scarabs emerge mid-June and can be active until August.
Iowa State University
Hodgson, Erin W., "Scouting for Japanese Beetle" (2012). Integrated Crop Management News. 210.
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