Kudzu Bugs Annoy, but Their Real Hunger Is for Bean Plants

— Written By and last updated by Diane Lynch

Q:  I have these brown, square-shaped bugs in big clusters on some of my plants. What are they and how do I control them?

 A: This sounds like the unwelcomed kudzu bug. Kudzu bugs are a new insect just making their appearance in the last couple of years. This insect originated from Asia and was first noted in the Atlanta area of Georgia in 2009. It is thought that the kudzu bug was accidentally introduced through the Atlanta airport. Since arrival, they have been spreading through out the South.

Kudzu bugs are easy to identify. They have square bodies and are brown to olive-green in color. They are a member of the stink bug family and emit an unpleasant odor similar to stink bugs. Their life cycle includes them overwintering under tree bark, in mulch or within house walls. They emerge in spring as adults and wait for kudzu to start growing. The kudzu vine is where they will lay their eggs and then die. The eggs will hatch in summer and feed on kudzu and other plants in the bean family.

From the insect’s name you can easily guess their main diet consist of the invasive vine, kudzu, which was also came from Asia. Kudzu bugs do not feed on every plant they are found on. They feed only on plants in the bean family. Some plants, besides kudzu, that are in the bean family include wisteria (also from Asia), butter beans, green beans, field peas, soybeans, and peanuts. Kudzu bugs feed on these plants using their piercing-sucking mouth part to pull sap from the plant. Symptoms that will show up due to kudzu bugs includes stunting, wilting, brown leaf edges, and dropping of flowers and seed pods.

Even though they only feed on plants in the bean family, kudzu bugs can be found in large clusters along the stems of other plants. Even though they are found on other plants, they are not damaging plants not in the bean family. The insect is attracted to light colors and can be found covering light colored things like sides of houses, tree trunks or vehicles. Finding kudzu bugs on these things should not cause alarm because they won’t cause damage.

The big questions most people want to know is should they be controlled. Since this is a new insect, there is still much being learned about what the best control practices will be. In most cases control measures will not be necessary where the insects do not pose a threat of causing damage. Spraying an insecticide will only temporarily discourages the bugs and will not provide long term control.

It maybe necessary to control kudzu bugs on bean plants to prevent reductions in yields. Insecticides recommended for control in this situation would be synthetic pyrethroids. Chemicals with this active ingredient include bifenthrin, permethrin, cyfluthrin, and lamda-cyhalothrin. It is important to note this group of insecticides is toxic to bees and other beneficial insects. Spray late in the evening when bees are not active to minimize risk. Organic pesticides have been found to have little impact on this insect. Pyrethrins are an organic option that can provide fair control. When finding a type of pesticides, check the active ingredients listed in small print on the front label to insure that you are selecting the correct one.

For your gardening, landscape, and lawn questions contact the Wayne County Extension Master Gardener Volunteer Plant Clinic on Mondays and Wednesdays from 10 a.m. to 1 p.m. The plant clinic is a free service open to any citizen in Wayne County that has home gardening questions. One can reach the Wayne County Extension Master Gardener Volunteer Plant Clinic by phone at 919-731-1433, e-mail at Master.Gardener@waynegov.com, or stopping by Room 100 of the Wayne County Extension Office (208 West Chestnut Street, Goldsboro). People contacting the plant clinic with questions are encouraged to bring samples and/or pictures that could help in reaching a solution. Extension Master Gardeners are trained volunteers with the Wayne County N.C. Cooperative Extension Service.

Recommendations for the use of chemicals are included in this article as a convenience to the reader. The use of brand names and any mention or listing of commercial products or services does not imply endorsement by the North Carolina Cooperative Extension Service nor discrimination against similar products or services not mentioned. Individuals who use chemicals are responsible for ensuring that the intended use complies with current regulations and conforms to the product label. When using any pesticide always read and follow all label directions.

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Jessica Strickland
Extension Agent
North Carolina Cooperative Extension
Wayne County Center
P. O. Box 68
Goldsboro, NC 27533
E-Mail: jessica.strickland@waynegov.com
Phone: 919-731-1525
Fax: 919-731-1511