Homeowners and soybean growers in North Carolina are in for a surprise this year, as kudzu bugs continue their march across the Southeast.

This invasive pest congregates en masse on home siding and legumes, like soybeans.

The insects were first found in Georgia in 2009, and since then, they have been found in soybean fields there and in South Carolina in large numbers. In 2010, one North Carolina county reported the pest, and last summer, it had spread to roughly half the state’s counties.

While kudzu bugs feed on legumes, masses of the insects are found congregating on plants they don’t feed on, like fig trees, crepe myrtles, grapes, wheat, cotton, corn and magnolia trees, among others.

During the week of May 14, kudzu bugs had been reported in six North Carolina counties in soybean fields, according to Dominic Reisig, North Carolina Cooperative Extension entomologist and North Carolina State University assistant professor.

Prior to this, kudzu bugs had mainly been found on patches of soybeans that came up voluntarily at the edge of fields and in soybean fields during mid- to late-summer.

And while the good news is that the insect does eat kudzu — another invasive species that all but swallows parts of the Southern landscape in summer — it isn’t likely to kill much of it, Reisig said. But it has been shown to reduce kudzu biomass.

Kudzu bugs are about one-quarter inch in size, somewhat oblong in shape and olive-green colored with brown speckles. With their piercing-sucking mouthparts, kudzu bugs feed on plants by sucking nutrients from leaves and stems. Though they don’t damage soybean pods like some other insect pests, they can induce stress in the plants, reducing yields.

The insects, which originated in Japan, are believed to have entered the United States near Atlanta, Reisig said. North Carolina entomologists have joined with researchers in South Carolina and Georgia to find effective strategies for managing this new pest. But right now, no one has much to offer, he said.

Many unknowns

“We don’t know what kudzu bugs will do this year to yields,” Reisig said. “We’re taking calls on a case-by-case basis. We give growers the information we have and let them decide what to do.”

Reisig and Jack Bacheler, North Carolina Cooperative Extension entomologist and North Carolina State professor, have developed a fact sheet about treating crops to protect against this pest. Entomologists in North and South Carolina and Georgia are collaborating to come up with answers for growers.

The kudzu bug’s preference for various types of plants seems to be controlled by bacteria that the insect carries on its body. The bacteria are also deposited when the kudzu bug lays its eggs to give offspring some direction on food preferences.

In Japan, the kudzu bugs don’t seem to have a preference for soybeans, but here, it eats any type of legume. “So the question is, how did it get bacteria that makes it feed on soybeans?” Reisig asks.

For homeowners, kudzu bugs pose different problems, said Mike Waldvogel, North Carolina Cooperative Extension entomologist and North Carolina State associate professor. This time of year, homeowners may find them feeding on wisteria or simply congregating on home siding. They seem to be attracted to light colored surfaces, he said. They also congregate on plants they don’t feed on, including those mentioned above.

“It’s a new pest. We’re still getting a feel for what chemicals are most effective in controlling it,” he said.

Waldvogel cautions homeowners against spraying insecticide on overhead surfaces like siding, where residues will certainly fall back on the person applying the pesticide and also run off into storm water.

Some North Carolina homeowners have reported finding kudzu bugs congregating on wisteria. To treat the insects on outdoor plants like wisteria and ornamental fruit trees, Waldvogel recommends using an insecticide labeled for the particular type of plant that is infested.

In the fall, homeowners may find the bugs congregating indoors, and again, Waldvogel cautions against using pesticides to kill the bugs inside the home. The first line of defense is sealing gaps and openings (around plumbing and air conditioner lines) to prevent the bugs from entering the home.

One effective approach is to vacuum them up and throw out the bag, as described in a North Carolina Cooperative Extension fact sheet http://www.ces.ncsu.edu/depts/ent/notes/Urban/kudzubug.htm.

Waldvogel also recommends contacting your local county Extension center for the latest information on controlling this pest. To find your county center, visit: http://www.ces.ncsu.edu/counties.

While kudzu bugs don’t bite like mosquitoes, bedbugs or ticks, they can cause skin irritation. Whether through a bite or skin reaction, anecdotal reports indicate that welts can appear on skin where the kudzu bugs are encountered, Waldvogel said.

More information about kudzu bugs on crops can be found at http://ipm.ncsu.edu/cotton/insectcorner/PDF/Kudzu%20Bug%20Handout_Field%20Crops.Final.pdf.

More information for homeowners about controlling kudzu bugs is athttp://insects.ncsu.edu/Urban/kudzubug.htm.