Japanese Beetles spend the bulk of their life underground going through 5 larval instar stages, pupating, and emerging from the soil as adults. Once out of the soil, the Japanese Beetle only goes back under the soil to lay eggs.
After feeding and mating, the female will fly down to the soil where they can burrow down 2-4 inches and lay their eggs where they can absorb moisture. The female then returns to the food source to start the process over again.
