Japanese beetle pupae start cream-colored and age to reddish-brown. As the soil warms, the larvae burrow toward the surface to change into beetles. The pupating stage lasts about two weeks.

Females lay 40 to 60 eggs in the topsoil in clusters. “In about 14 days, Japanese beetle eggs hatch and [grubs] burrow into the soil where they start feeding on the roots of plants and other ...