Kudzu bugs have a very dark side

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We have some fairly new insects to contend with – kudzu bugs. I had the first one brought to my office from Wilkes County in 2010. They first showed up in 2009 in Georgia in a nine-county cluster that included Oglethorpe, Clark, Oconee, Jackson, Barrow, Hall, Gwinnett, Walton and DeKalb. The bugs have been spreading every year and now reach into South Carolina, North Carolina and southernmost Virginia. Going West, they have reached a few counties in Alabama. As far as I know, the only areas in Georgia that have not been infested are coastal and extreme south Georgia.

Kudzu bugs came from Asia; scientists think from Japan. They had never been seen in the western hemisphere until the fall 2009, when they showed up in these clusters of Georgia counties.

Kudzu bugs are about 1/6- to ¼-inch long, somewhat oblong in shape, and olive-green with brown speckles. They have a squared-off back end.

These insects get their name because kudzu is their favorite meal. Unfortunately, they don’t stop at kudzu. They will feed on a variety of legumes (soybeans and other bean species as well as wisteria and some vetches).

Not only are they causing a concern for plants, they are a nuisance because they like to come in our houses in the fall.

Kudzu bugs have several generations per year. In the spring, they feed extensively in kudzu patches and on other legume hosts. In July and August, they move into soybeans and feed on stems and foliage, having a significant impact on crop yields. The bugs continue to feed and lay eggs into the fall on kudzu and other hosts.

As the temperature and day length decline, kudzu bugs leave their soybean and kudzu hosts in search of protected sites where they will spend the winter. Overwintering sites are any crack or crevice where a group of bugs congregate. For example, this can be, but is not limited to, the gaps under the bark of trees or under the siding of a home. They seem to like high places as well, such as the edges of homes (fascia boards, gutters). During each of the past three years, this fall flight began around mid-October and did not subside until late November or early December.

When bugs find their way in your home, vacuum them up and make sure you seal all cracks and crevices and make sure window screens are repaired and door sweeps are installed. When bugs congregated on your house, spray them directly with a pyrethroid insecticide. Do not spray indoors.

For any plants in the garden such as peas or beans, any number of insecticides such as carbaryl (Sevin), bifenthrin (Ortho Max Bug-B-Gon), spinosad, or esfenvalerate can be used as kudzu bugs are easily killed. Unfortunately, new kudzu bugs will quickly re-infest plants.

Kudzu bugs have reduced kudzu growth in Georgia by 30-50 percent. The bad news is they are having an impact on Georgia soybean production by reducing yield around 20 percent. There also does not appear to be very many native natural enemies of kudzu bugs. As a result scientists have searched for and identified a parasitoid in Japan. Plans are to import this wasp for biological control purposes. The wasp parasitizes kudzu bug eggs, thus ending their life cycle.


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