Written by: Charlotte Glen, Horticulture Agent
There is a new bug in town and chances are if you have wisteria growing in your yard you have already met it. Officially known as the bean plataspid, this new insect is more commonly being referred to as the kudzu bug, after its favorite food. But it is not exclusive to kudzu and will happily feed on wisteria and other members of the bean family.
Where Did They Come From?
Kudzu bugs are native to China and India and had never been seen in the western hemisphere until the fall of 2009. Lucky for them they landed in one of the largest kudzu patches in the world – the state of Georgia. In just a little over two years these small but highly mobile insects have spread throughout Georgia and South Carolina, into Alabama, and can now be found in most of North Carolina’s 100 counties. They were first recorded in Pender, New Hanover, and Brunswick counties last fall.
Their introduction is believed to have been accidental, and could possibly have occurred through the Atlanta airport. It is expected their rapid spread will continue throughout the kudzu infested south. Kudzu, which hails from China and Japan, is considered a highly invasive species in the United States. Though intentionally cultivated for erosion control and animal feed in the early 1900’s, it quickly spread out of control and has since come to be known as “the vine that ate the South”.
Do They Cause Any Problems?
At first glance the arrival of the kudzu bug seems like a good thing since it helps control kudzu. Unfortunately it is not that simple because they can feed on any member of 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.
Their impact on soybean production is particularly worrying, considering North Carolina is the largest soybean producing state on the east coast, annually growing over one million acres. In a study conducted in Georgia in 2010, untreated fields experienced yield reductions of 20 percent or greater, directly reducing farm profitability.
For home gardeners it is not yet known how much impact kudzu bugs will have on ornamentals and vegetables. They have been widely reported on wisteria in our area this spring, but it is thought they are just feeding on the wisteria until the kudzu starts growing. If that is the case, and they move on to kudzu in the next few weeks little damage will be done. If they continue to feed on wisteria all season it is more likely they will damage the plants. It is uncertain how much damage they may cause to summer crops of butter beans, green beans, and field peas.
Though they are only known to feed on plants in the bean family, kudzu bugs will congregate in large numbers on many plants as well inside and outside of homes. They are attracted to light colors and have been documented in the thousands covering sides of houses, tree trunks, and even light colored vehicles. During winter they often come indoors by the droves, though this behavior has not yet been observed in our area. They do not cause damage inside the home but are considered a nuisance pest and can be removed with a vacuum cleaner.
Should They Be Controlled?
Kudzu bugs do not eat plant leaves or stems. Instead they feed on plant sap using their piercing sucking mouthparts, which are shaped like a hypodermic needle. Symptoms caused by heavy feeding include stunting, brown leaf edges, wilting, and dropping of flowers and seed pods. On ornamental plants like wisteria control is usually not necessary unless the insects occur in very large numbers on young plants. Since the insects tend to congregate in large clusters, one of the easiest ways to control them is to knock them off the plant into a bucket of soapy water where they will drown. Spraying pesticides may discourage these bugs temporarily, but does not provide lasting control. Insecticides containing carbaryl (Sevin), malathion, permethrin, or bifenthrin will kill insects when sprayed, but new kudzu bugs will quickly re-infest plants. Organic insecticides will likely have little to no effect on this insect.
Hopefully this summer these bugs will stay in the kudzu rather than move into home vegetable gardens where they could feed on butter beans, green beans, peanuts, and field peas. Gardeners will need to keep a close eye on these crops this season and contact their local Extension office for control recommendations if they become a problem.
Learn more about kudzu bugs from these great links:
- Here Come the Kudzu Bugs, article by Lee County Extension Agent, Brenda Larson: http://lee.ces.ncsu.edu/index.php?page=news&ci=LAWN+317
- Kudzu Bugs – how to deal with inside the home from NC Cooperative Extension: http://www.ces.ncsu.edu/depts/ent/notes/Urban/kudzubug.htm
- Kudzu Bugs in field crops from NCSU (pdf file) – includes good pictures of all stages of this insect’s life cycle and a distribution map:http://ipm.ncsu.edu/cotton/insectcorner/PDF/Kudzu%20Bug%20Handout_Field%20Crops.Final.pdf
If you have questions about gardening contact your local Cooperative Extension office:
- If you live in Pender County call 259-1235, or visit us online anytime at http://pender.ces.ncsu.edu/index.php?page=askanexpert, where you can post your questions to be answered by email using the ‘Ask an Expert’ widget!
- If you live in New Hanover County, call 798-7660, or post your questions here: http://newhanover.ces.ncsu.edu/index.php?page=askanexpert
- If you live in Brunswick County, call 253-2610, or post your questions here: http://brunswick.ces.ncsu.edu/index.php?page=askanexpert
- If you live in Onslow County, call 455-5873, or post your questions here: http://onslow.ces.ncsu.edu/index.php?page=askanexpert
- For other counties, find your local Extension office: http://www.ces.ncsu.edu/index.php?page=countycenters
Visit the Pender Gardener blog to stay up to date with all the latest gardening news, http://pendergardener.blogspot.com/.
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