STARKVILLE, Miss. — After just one year in Mississippi, invasive kudzu bugs are becoming a management headache in soybeans and a pest in houses. And the pea-sized, squarish bugs made their way into Louisiana this year, probably as hitchhikers.
Farmers and entomologists in both states had been watching for an invasion since July 2012, when kudzu bugs were spotted in Vicksburg — about 270 miles west of the nearest Alabama county where they’d been seen.
In June, the LSU AgCenter confirmed the bug’s arrival in a soybean field in Madison Parish. By the end of July, it had been found in 17 Mississippi counties, and in soybean fields in seven of those counties.
Mississippi’s highest numbers were in the southwest, near Warren County, said Angus Catchot, entomologist with the Mississippi State University Extension Service.
“Every week or two, someone finds low numbers of kudzu bugs in some other part of the state,” Catchot said. “So far we have low numbers, but they multiply very quickly. In two to three years, they’ll probably be commonplace.”
Both states want farmers who spot the bugs to tell their county or parish agent.
Kudzu bugs range from green to a brown so dark it’s almost black. They look a bit like ticks and a bit like dark ladybugs with squareish backsides.
In the bug world, they’re famous as hitchhikers. Most of the places they were first spotted in Mississippi were heavily travelled areas near gas stations with nearby kudzu plants.
“Once they’ve had a chance to colonize, they start dispersing in high numbers,” Catchot said.
The bugs, which are as fond as soybeans as they are of kudzu, also have been found in North Carolina, Virginia, Georgia, Tennessee and Alabama.
“We don’t want to alarm our growers,” said LSU AgCenter area agent Sebe Brown. “We just want to make them aware that the insect is here. If they have fields along the Mississippi River, especially in Madison Parish, they need to scout for the insect as they look for stink bugs or any other insect populations.”
He said preliminary data from the University of Georgia show that heavy infestations will cause yield losses averaging 18 to 20 percent.
They don’t eat beans but suck on stems and leaf-stalks. Insecticides used on stinkbugs will kill them.
“Our biggest challenge is educational,” Catchot said. “They’re not real damaging in low numbers, so we’re encouraging our growers to not get upset when they see a bunch in the field. Wait until the insects have finished migrating into the field and then spray.”
Adult kudzu bugs might move into a field for four to six weeks, and spraying too early will let later arrivals re-infest the field, Catchot said..
“We recommend that growers not make an application of insecticide until they scout and find one immature kudzu bug per sweep with the net,” Catchot said. “Once you start picking up immature kudzu bugs, it’s a good sign that the adult migration is over. One well-timed spray should be sufficient.”
Like ladybugs, they’re attracted to light surfaces and can cluster on buildings in the fall in great numbers, looking for a crevice through which they can enter to spend the winter in warmth. And they can squeeze in through a one-eight-inch gap.
“Exclusion rather than insecticide use is the best defense,” Layton said. “Seal cracks, crevices and tears in screens over windows and gable or soffit vents. The house may have been sealed tight when it was built, but over time, crevices can develop.”