Though the brown marmorated stink bug has only been sighted a few times in Iowa, experts say the bugs could expand rapidly and create a serious problem for farmers and homeowners.
The stink bugs are classified as an agricultural pest. They are native to Asia, particularly China, Japan, and Korea, though they have recently appeared in the United States.
“They’re easy travelers,” said Robin Pruisner, the state entomologist at the Iowa Department of Agriculture. “They can crawl into a box and move to other areas. So we don’t know if [a particular bug] was born here or traveled.”
Pruisner said department officials have found three bugs in various areas around Iowa, with Johnson County being one of the areas, though estimates of the current stink-bug population were virtually impossible to make.
James Lacina, the environmental health coordinator for the Johnson County Public Health Department, said it hasn’t received any calls about stink bugs yet, but officials would investigate the issue if it was brought to their attention.
Pennsylvania faced a similar invasion in the early 2000s, which caused severe damage to apple and peach crops in the state, and there were still reports of damage in 2010.
Matt O’Neal, an assistant professor of entomology at Iowa State University, said the bugs cause damage to plants and crops by sucking out the insides, destroying seeds and other material inside.
“You often don’t see feeding damage until months later,” he said. “It causes apples to rot from the inside out.”
Pruisner said if the stink-bug population grows, it could affect corn and soybean crops in particular, two crops that are very prevalent in Iowa.
Stink bugs don’t only affect crops. They can also be a very smelly nuisance to homeowners.
“When the winter comes, stink bugs like to find a cool, protected place and hibernate,” Pruisner said. “But if they crawl into houses, they may stay active.”
Pruisner said she has not heard of any more than one in Iowa houses as of yet. But even one can create an odor if stepped on.
“They have a very distinctive odor,” she said. “People report a burnt rubber type of smell. It’s a very bizarre smell combination that can be pretty upsetting to homeowners.”
Unfortunately for homeowners, the bugs can get so numerous as to require pest-control intervention.
“There’ve been reports of people removing bucketfuls [of stink bugs] from their homes,” O’Neal said. “Many insecticides just don’t seem to be effective.”
Pruisner said females average around 250 eggs in a lifetime, and that with varying environmental conditions there can be between one and six generations of stink bugs in a year.
O’Neal said the number of stink bugs could expand rapidly.
“If they get established, there could be hundreds of thousands of stink bugs in Iowa,” he said.
As for how a stink-bug problem could be combated, O’Neal said it depends.
“The real ‘silver bullet’ for invasive species is to use importation,” he said. “That is, going to where the species is native and finding a natural enemy that only attacks the invasive species and releasing it here. In some cases that resulted in dramatic decreases [of the invasive species], but it doesn’t always work.”