Kudzu bugs are here; problem is (besides the stink), they may eat more than kudzu

photo Kudzu bugs, like these on Missionary Ridge, have made their way in eastern Tennessee, as well as Florida, Alabama, North and South Carolina, Virginia and Washington, D. C. The bugs eat kudzu and soybeans and emit an odor like a stink bug when disturbed.

ABOUT KUDZU BUGS• Adults are 0.13 to 0.23 inches long, oblong, olive-green colored with brown speckles and produce a mildly offensive odor when disturbed. In the United States, characteristics of the adult kudzu bug useful in distinguishing it from other stink bugs (Pentatomoidea) include: The plate in the center of its back (the scutellum) is broader along the bottom than it is along the top, and much wider than it is long.• The kudzu bug is a relatively new pest in the United States. Researchers are still working on developing better ways to manage this pest in all of the different environments it is found. Contacting your state extension service is the best way to get recommendations that are tailored to your specific situation.• Depending on temperature, it takes approximately 6 weeks for a kudzu bug to go from an egg to an adult. Current research has found that there are two generations of kudzu bugs in the Southeast each year. Much of the kudzu bug populations develop on kudzu or wisteria for the first complete generation, and the second generation completes its development on soybeans and other cultivated and wild hosts (kudzu, wisteria, etc., included). Overall, second generation kudzu bugs have a preference for bean-related plants.Source: kudzu.com, clemson.eduPREVENTION AND CONTROL• Cut back any kudzu or wisteria you can.• Seal cracks and crevices in your home.• Clean the area inside the house where bugs have appeared with soap and water.• Large numbers of bugs should be vacuumed, not sprayed. Use a shop vac with soap and water inside to clean up the bugs since the odor will linger in a conventional vacuum cleaner.• Conventional bug sprays will kill the bugs, but make sure you use one that is safe for plants.• Avoid squashing the bugs since their residue will leave a stain.Source: clemson.edu

photo Distribution of the kudzu bug from 2009 to 2013.

They might be small in stature, but kudzu bugs are quickly becoming a big -- and smelly -- problem across the South. In fact, entomologist Wayne Gardner at the University of Georgia at Athens, says their arrival and the recent discovery of a parasitic enemy that specifically targets the insects is like something out of a Michael Crichton novel.

"They are not supposed to have appeared in North or South America, and they turn up on our front porch, or back porch, however you want to look at it," he says.

The tiny bugs, which look like an olive-green version of a ladybug, first showed up at Hartsfield-Jackson Atlanta International Airport in 2009. They likely came over on a plane from Asia, where they are prevalent.

Since arriving, they have migrated into North and South Carolina, Virginia, Alabama, Florida and Tennessee. Their primary dietary source is kudzu, which might be welcome news, but scientists fear they might also like soybean plants, which are similar to kudzu.

And, the insects, which are strong flyers, travel in large numbers. Lately, local kudzu vines have been covered in the smell-spewing bugs.

"They are gregarious, meaning they gather in large numbers," says Dr. Marianne Shockley, a faculty member in the entomology department at UGA. "You don't just see one, you see hundreds."

But for local homeowners, they're more of a curiosity at this point than a problem, according to Rick Anderson with Arrow Pest Control.

"I've had three or four calls from people really just wanting to know what they are."

Gardner says that may change in the coming weeks as the weather cools and the bugs look for warm places to spend the winter. They are attracted to light-colored surfaces, especially white houses, he said.

The bugs, which Shockley says "are on every entomologist's radar," use piercing, sucking mouthparts to extract the vascular, nutrient-carrying tissue from the plant, so the damage is more from a loss of nutrients and moisture than from eating the plant itself. The larger adult insects feed on stems, while the small nymphs can be found under the leaves, feeding on the veins.

They don't bite and they are not harmful to humans, but when squashed or irritated, they emit a potent odor similar to their larger cousins, the brown marmorated stink bug that's familiar to most Southerners.

The big worry, though, is what they might do to plants other than kudzu, especially soybeans and other legumes. Shockley says that, so far, she hasn't seen enough scientific proof to determine whether the bugs will eat the cash crop.

"To my knowledge, we haven't yet seen an economic impact," she says.

However, according to a North Carolina State University report, a research station in Midville, Ga., (located about halfway between Macon and Savannah), showed soybean yield losses up to 47 percent on untreated beans in 2011. The station reported finding just two kudzu bugs at the site the year before.

photo Kudzu bugs, like these on Missionary Ridge, have made their way in eastern Tennessee, as well as Florida, Alabama, North and South Carolina, Virginia and Washington, D. C. The bugs eat kudzu and soybeans and emit an odor like a stink bug when disturbed.

ONLINETo see a map detailing the spread of the kudzu stink bug, go to kudzubug.org/distribution_map.cfm.

Johnny Dodson, a corn, cotton, wheat, beef and soybean farmer in upper west Tennessee, says the insects have not been identified there, but as a member of the American Soybean Association and the state's representative on the national level, he is keenly aware of them.

Farmers are working with entomologists at the universities of Florida, Georgia, Alabama and Tennessee to watch and learn as much as they can about the new threat.

"It's new to us and, as far as we are concerned, there will be things that we will have to learn, such as how much damage can they do before you need to spray and is the soybean more sensitive to them," Dodson says. "We don't want to make an expensive pesticide application when it's not necessary and, as farmers, we don't want to make an application at all, but we have to protect our crop. It's a balancing act."

Gardner said scientists just recently have found that when farmers spray can have a significant impact on preventing the bugs from destroying a farmer's crop.

They are getting really close to figuring that out, he says, and it looks like one well-timed application can last an entire season. That doesn't seem to work with home applications because there is not enough residual effect of the chemicals.

"You can kill off a swarm, but they are replaced few days later," he says.

Scientists are studying the kudzu bug from several angles, including how to get rid of them entirely, Shockley says.

"That is the million-dollar question."

Contact staff writer Barry Courter at bcourter@timesfreepress.com or 423-757-6354.