October 25, 2013
(Editor’s note: The article was written by Jessica Strickland and Tyler Whaley, Wayne County extension agents, and provided by the Sampson County Cooperative Extension Service.)
We have had many, many calls in the last couple of days about bugs being seen on everything from house siding, cars, to plants. These bugs are often described as brown, square-shaped. This bug is 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 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, driveways or vehicles. Finding kudzu bugs on these things should not cause alarm because they won’t cause damage.
The big question 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. It not recommended to spray an insecticide when the kudzu bug is found in most places because spraying an insecticide will only temporarily discourage the bugs and will not provide long term control. Spraying with an insecticide will not eliminate the kudzu bug and will often end up being a waste of time and money spent on the insecticide. Instead, the best control measures would be to simply sweep, brush, or vacuum them away when they are found on doors and windows of a house.
If you find them clustered on plants, the simplest control is to shake the insect off the branch into a bucket of soapy water to drown them. The only time insecticides are recommended to control kudzu bugs are on types of bean plants to prevent reductions in yields. However, since many types of bean plants—-such as soybeans—-have reached maturity there is little reason to control now. Also, insecticides have only been found to discourage kudzu bugs and not been found to provide good, long-term control. Insecticides that would be recommended for control on soybean plants 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.
Kudzu bugs seem to have been appearing when we get a little bit of sunshine and warmer temperatures. They are a nuisance however they when we get into more consistent cool weather patterns they will begin to go away. Even though seeing kudzu bugs on or around a house causes concern, they do not damage your home or harm you if you come in contact with them. They are simply a pest that we will have to live with for a short period of time until they go away to overwinter.
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.