Fewer Japanese Beetles This Year

Have you noticed fewer Japanese Beetles on your plants this year? That's because the winter killed off a lot of the underground grubs.

According to the Univ. of Illinois Extension Newsletter (June 16, 2014), "Research has shown that Japanese beetle grubs do not migrate deeper than 11 inches into the soil for the winter. They die if the soil temperature reaches 15 degrees F or if they are subjected to freezing temperatures for 2 months."

Adult Japanese Beetles appear in late June and die off in about 60 days, after they have mated and the females have laid eggs in the soil/turf. You won't see any adult beetles here in September--but the grubs will be growing in the soil and moving deeper as the weather gets colder. The beetle is entirely dependent on these grubs, which start growing again as the weather warms up in May, for their existence.