The return of spring has tempted more than gardeners to venture outside and enjoy the warm weather. Kudzu bugs, a new insect first seen in our area in 2011, are coming out from their winter hiding places by the thousands. Slightly larger than a lady bug, with olive green or brown flattened, square bodies, kudzu bugs are strong fliers and often gather in large groups. If you spend time outside in the next several weeks chances are you will run into them.
Do They Cause Any Problems?
Originally from Asia, kudzu bugs were first found in the United States near Atlanta, Georgia in the fall of 2009. They are believed to have been accidentally introduced through the Atlanta airport. Since landing on American soil they have spread throughout the southern states, anywhere their favorite food, kudzu, grows. Kudzu, which is also from Asia, is an invasive weed sometime referred to as ‘the vine that ate the South’.
Kudzu bugs only feed on plants in the bean family. This includes ornamental plants like wisteria, also from Asia and a favorite of the insect, as well as edible crops like peanuts, soybeans, butter beans, green beans, and field peas. Kudzu bugs do not eat plant leaves or stems. Instead they feed on plant sap with their piercing mouthparts, through a process similar to drinking liquids from a straw. Symptoms caused by heavy feeding include stunting, brown leaf edges, wilting, and dropping of flowers and seed pods.
Though they only feed on plants in the bean family, kudzu bugs often congregate in large numbers on many plants including figs and fruit trees, but they do not cause any damage to these plants. They are attracted to light colors and often cover sides of houses, tree trunks, and even light colored vehicles. Kudzu bugs will not damage your house or harm you if you come in contact with them, though as a member of the stink bug family they do emit an unpleasant odor and may stain surfaces when crushed.
The current infestation of kudzu bugs are adults that overwintered under tree bark, within house walls, or in mulch. These adults are waiting for the kudzu to start growing. As this happens over the next month, they will fly into the kudzu, lay their eggs, and then die. A new generation will hatch and feed on kudzu and other bean plants through the summer.
Should They Be Controlled?
On ornamental plants like wisteria control is usually not necessaryunless the insects occur in very large numbers on young plants. On mature wisteria vines, heavy feeding by kudzu bugs may cause stunting and can reduce or delay flowering, but at this point it is too late to treat to avoid impact to this year’s flowers. It is usually necessary to treat kudzu bugs on bean plants to prevent a reduction in yields. Since these insects tend to congregate in large clusters, one way to control them is to knock them off plants into a bucket of soapy water where they will drown.
Spraying insect killers discourages these bugs temporarily, but does not provide lasting control. Large scale spraying of lawns, house siding, or plants that are not in the bean family is not recommended and will not get rid of these insects. Keep in mind the large number of adults currently present will greatly decrease in the coming weeks.
To control kudzu bugs on beans and plants in the bean family, insecticide sprays containing a synthetic pyrethriod as the active ingredient are most effective. These include the chemicals bifenthrin, permethrin, cyfluthrin , and lamda-cyhalothrin. Name brands of some insecticides that contain these chemicals include Ortho Bug B Gone Max Concentrate, Tiger Brand Super 10 Concentrate, Bonide Eight Insect Control Concentrate, and Spectracide Triazicide Insect Killer Concentrate. Always check the active ingredients listed on the front of the pesticide label to make sure you have the correct product. Before spraying, consider the impact these products have on beneficial insects. Synthetic pyrethroids are toxic to bees and beneficial insects that naturally help to keep pest populations in balance. To minimize impact, only spray infested plants. Spray late in the evening when bees are no longer active.
Organic pesticides have little impact on this pest, though products containing pyrethrins, the natural compounds upon which synthetic pyrethroids are based, may be slightly more effective than others. Please note: Recommendations for the use of insecticides are included in this article as a convenience to the reader. The use of brand names does not imply endorsement by North Carolina Cooperative Extension nor discrimination against similar products not mentioned. When using any pesticide always read and follow all label directions.
More information about kudzu bugs is available online at http://insects.ncsu.edu/Urban/kudzubug.htm.
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Visit your local Cooperative Extension office to learn more about gardening and landscape care. Go to https://www.ces.ncsu.edu/local-county-center/ to find your county Extension center or post your questions to be answered online via Extension’s ‘Ask an Expert’ widget.
- If you live in Pender County, call 910-259-1235
- In New Hanover County, call 910-798-7660
- In Brunswick County, call 910-253-2610
- In Onslow County, call 910-455-5873
- In Duplin County, call 910-296-2143
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