Remember last year’s summer and fall drought? Remember grumbling about the long, cold winter we experienced after? Have you noticed there are very few Japanese beetles ravaging your 2014 growing things? The two are connected.
University of Illinois Entomologist Phil Nixon predicted this would occur. He estimated 2/3 of the future pestilence died of natural causes in the ground.
He explained two subsequent weather events caused the death of Japanese beetle larvae in mass numbers.
- The larvae require about 11 inches of water, from the egg hatch in late July into the fall. Last year, from July through October, rainfall averaged 9.5 inches in most of Illinois and [only] 6.67 inches in Davenport[, IA.]
- 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, or if they are subjected to freezing temperatures for two months. This past winter, the soil was frozen 15 to 30 inches deep in much of Iowa and Illinois for several weeks.
