The stink bugs, known to feed on more than 300 varieties of host plants, resulted in about $37 million in losses from damage to apple crops alone in 2010; crops of raspberries and blackberries were also ravaged, and many organic farmers saw significant damage to crops of tomatoes, peppers and beans, experts reported.
Lawmakers, entomologists and the agricultural community scrambled for a solution to a problem that was only expected to worsen. The Environmental Protection Agency in 2011 approved an exemption for a highly toxic insecticide to help growers fight the insects. Homeowners braced themselves for the unwelcome presence of the bugs, which seek sheltered places — such as houses, garages and barns — to hibernate for the winter. Farmers prepared for another year of battle in their fields, orchards and vineyards.
But then scientists and farmers alike noticed a sudden and dramatic decrease in the number of stink bugs during the fall of 2011. Entomologists are still unsure how to explain the change. It’s possible, they said, that a succession of strong storms late that summer culled the population.
“Just when it was getting really bad, it started getting better,” said Doug Fabbioli, a fruit grower and winemaker who owns Fabbioli Cellars in Leesburg.
But now, scientists caution, the insects appear to be resurgent.
Christopher Bergh, a Virginia Tech associate professor of entomology, said the overwintering population of bugs this past fall was “substantially larger” than that observed in 2011.
“I don’t want to raise any red flags unnecessarily,” he said. “But growers are going to definitely need to remain vigilant starting in the 2013 season.”
Bergh said the early arrival of spring last year also helped farmers and growers avoid the worst of the bugs; many early-season crops got a head start on the insects, which then emerged in smaller numbers.
“There was less opportunity for them to do damage,” he said.
But Tracy Leskey, a research entomologist with the Agriculture Department, said the reduced population of bugs “essentially rebounded over the course of the growing season” last year, and homeowners saw far more bugs come inside to spend the winter than they did the year before.
“We have been trapping in the late season, and we know the populations are probably at least 60 percent greater this year compared to ,” she said. “If they survive over the winter, there will be many more bugs in the spring.”
At Butler’s Orchard in Germantown, co-owner Wade Butler said he and other employees discovered swarms of the insects recently while working in one of the farm’s open barns.