If you've been growing soybeans in Arkansas the last couple of years, you probably came face to face with a serious new threat to your pocketbook — stinkbugs. The bad news is the problem probably is not going to be any better this year, say experts with the University of Arkansas Cooperative Extension Service.

“Stinkbugs have always been in Arkansas,” said Jeremy Greene, Extension entomologist at the Southeast Research and Extension Center in Monticello, Ark. Farmers see them every year. It's just that stinkbug numbers have exploded, he said.

Some fields were wiped out by stinkbugs, said Richard Klerk, Arkansas Extension area soybean agronomist.

“They started in the southeast corner of Arkansas and moved north. They were a problem for farmers as far north as Mississippi County in 2001. I expect them to be a continuing problem this season.”

Greene said there are more than 200 species of stinkbugs in the United States, but the most important species of concern to Arkansas farmers are the brown stinkbug, green stinkbug and Southern green stinkbug.

Stinkbugs are triangular or shield-shaped. The green species is the largest, approaching nearly three-fourths inch. The insect gets its name from the odor it gives off as a defense or attractant.

Stinkbugs will feed on any kind of plant that produces fruit or seed, including all major row crops, corn, pecans and tomatoes, Greene said.

Klerk said stinkbug levels were so high in some soybean fields last year that farmers had to treat the same fields twice in less than two weeks.

Greene said methyl parathion is a cheap and effective insecticide for stinkbug control in soybeans. Some pyrethroids are also effective, but they cost more.

Klerk said having to spray even once was a burden for many farmers.

“The low prices for beans deterred some farmers from spending additional money on the crop. There were situations, especially in south Arkansas, where some farmers suffered heavy yield losses and quality problems because they didn't have any money left to spray.”

Greene said the reasons for the explosion in stinkbug numbers aren't clear, but a couple of possibilities stand out.

“One factor might be the environment. We don't have normal weather patterns anymore,” he said.

Another possibility might be that this is part of the natural cycle for stinkbugs. Greene said insects go through upswing and declining periods during a cycle lasting years. He said farmers might have to endure a period of great numbers before stinkbugs decline naturally.

Greene said some farmers have pointed a finger at the boll weevil eradication program as a possible reason. He doubts this is part of the problem, noting, “Other parts of the state are not under the eradication program and still had tremendous stinkbug numbers.”

Greene said stinkbugs are mainly fruit-feeders, but they will also feed on leaves and stems of plants. The damage they cause can take the form of shriveled seed and reduced yield and oil content. If that weren't enough, stinkbugs have been associated with a devastating disease called green bean syndrome.

Klerk said the Arkansas Extension Service has been getting the word out about this problem at winter production meetings.

“We're emphasizing the problem in grower meetings and providing information for controlling the insects in soybeans and rice.” He said farmers must scout soybean fields weekly once plants begin blooming and determine if their numbers warrant treatment.

He said county agents will have the latest research and advice on how to deal with the problem.


Lamar James is an Extension communications specialist with the University of Arkansas.