Number of Japanese beetles emerging early 'nuts'
URBANA – The number of Japanese beetles emerging early in southern Illinois this month is off the scale.
But University of Illinois entomologist Kevin Steffey said that doesn't necessarily mean the hatch of the destructive beetles in East Central Illinois will be correspondingly enormous.
"I predict there will be Japanese beetles somewhere, but whether they'll be in large numbers, I don't know," Steffey said. "There might be places where there was significant winter mortality and other places where they were well protected. We'll know by the end of the month."
Steffey said findings of retired UI employee Ron Hines, who traps bugs in the southern part of the state for GROWMARK, were "nuts."
"The largest number from last year's capture the week ending July 4 was 155,000 beetles," he said. "But for the week ending June 19, 2007, they captured more than 309,000 beetles in Massac County."
That's more than 80 pounds of beetles, Hines reported on the UI's integrated pest management Web site.
"The highest single day capture occurred on Sunday when about 68,372 beetles, about 18 pounds, were captured," Hines wrote on the site. "The Massac and Pulaski sites have already set new one-week capture records and we're just past mid-June. Adult emergence occurs over an extended period of time. Crop producers should expect the beetles that emerged this week to stay around through the end of July."
Steffey said the beetles are showing up early this year.
"Insects to a degree are controlled by temperature, and both Japanese beetles and Western corn rootworms are emerging earlier than usual because of the warm weather," he said.
And Steffey's a little surprised because he expected the cold winter to kill many of the overwintering larvae.
At the end of the summer, the adult Japanese beetles lay eggs in the soil; white grubs hatch and feed on organic material and vegetation through the late summer and fall.
They overwinter as grubs and when the weather warms up in the spring, they start feeding again, pupate and emerge as beetles.
"There is ample evidence that a cold winter will kill the grubs because they're not that deep and they're not protected from cold temperatures," Steffey aid. "Our soil temperatures got down to the critical stage, 20 degrees, then it snowed, insulating the soil."
Voracious, destructive Japanese beetles annoy homeowners because they strip some trees of their leaves and feed on brightly colored flowers. According to UI Extension specialist Suzanne Bissonnette, they feed on more than 300 different kinds of plants.
Sheer volumes are annoying. Last year, homeowners in the Fisher area scooped up dead beetles by the buckets full.
And White Heath fruit and vegetable grower Richard Pontious told The News-Gazette the beetles had ruined 60 percent of his crops.
Steffey said farmers worry about the beetles feasting on corn silks so ears don't pollinate properly. He said dry weather's the real worry in corn fields now because it has put stress on the crop and insects do more damage to a crop that's already stressed.
"There always concern about good pollination when it's hot and dry, and you throw in the insects and you have a real mess," he said.