Glass Is Half-Full: Floods Reduce Insects

The only good thing that may have come from the floods in Indiana in May and early June is the reduction of crop insects because they weren’t able to survive the wet conditions, says a Purdue University expert.

"Right now we’re seeing extremely low numbers of corn rootworm beetles, specifically the Western corn rootworm beetle, as well as the Japanese beetle," says John Obermeyer, Purdue Extension field crops entomologist.

Obermeyer says the floods came about the time that the rootworm eggs hatch into larvae and the larvae had a very difficult time getting through the saturated soils and finding corn roots.

"The flood literally drowned them," Obermeyer says. "It seems the Japanese beetle, the grub portion of the biology, were also affected by the wet soil and possibly diseased by the fungal pathogens in the soil. So we are seeing extremely low numbers right now and I have received very few reports of concern about those insects feeding on corn, soybean foliage, even the silks."

The soybean aphid, which is typically building in numbers now in Minnesota, Wisconsin, North Dakota, and South Dakota, is virtually nonexistent this year, Obermeyer says.

Obermeyer doesn’t see how corn rootworm and Japanese beetle populations can rebound from this anemic state and expects numbers to be low for 2009, too. Don’t worry though, he says, they’ll be back.

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