Megacopta cribraria, bean plataspid, kudzu bug, lablab bug, globular stink bug... a kudzu bug by any other name still stinks
In 2009 this pest was officially recognized as infesting a portion of northeast Georgia. Entomologists investigating multiple requests for help discovered a thriving population of kudzu bugs. This was not a case of finding a few bugs. The area of confirmed infestation has quickly increased in area each year since. A current map at Kudzubug.org shows the insect now present in virtually all of Georgia and the Carolinas. Significant portions of Alabama, Florida, and Virginia now report this bug. Tennessee and Mississippi are starting to tally up affected counties as well. Genetic studies of sample bugs point to their origin from a single female bug somehow making its way to northeast Georgia. The insect is native where the kudzu vine is considered native: Asia and Australia.
Identifying kudzu bug
Individually, kudzu bugs look innocuous, even slightly comical. They have dumpy, round, drab, greenish brown bodies with a few faint yellowish spots — none of those classic bold "warning colors." (See the resources listed below for photos of kudzu bugs.) About the size of a ladybug, kudzu bugs are "true bugs." They feed by sucking plant juices. While kudzu vine is this beast's preferred host plant, kudzu bugs have discovered soybeans and begun damaging crops. The bugs prefer plants in the bean family, but are found in large numbers on other garden plants as well. In fall, kudzu bugs cluster on homes, seeking winter shelter. This habit will sound familiar to those of us already plagued by brown marmorated stink bugs. Thousands of bugs smothering one's green beans, or the side of one's home, are certainly no longer comical.
Expected range — far and wide
Kudzu vine is considered the primary host of the bug. "The South" has legendary growths of kudzu vine. But kudzu vine now grows as far north as Connecticut, and into the midwest plains of Kansas and Oklahoma. The Pacific Northwest has kudzu, as does Hawaii. The kudzu bug flies well, despite its unaerodynamic shape, and can be expected to soon range as far as the kudzu vine, at least to the east of the Rocky Mountains.
You'd think that a bug that sucks kudzu dry would be a blessing. Far from it. As the alternate name "bean plataspid" implies, it also infests bean family crops. It is already a major pest for soybeans, and here the comical bug becomes scary. Soybeans are the United States second largest agricultural crop, and the United States produces roughly one half of all soybeans grown worldwide. Kudzu bugs also damage crops of other edible beans, and are harbored in wild legume plants near fields. The bugs cause loss of 37% to possibly 75% in soybean yield. Kudzu bugs will complete their entire life cycle on soybean.
Gardeners and homeowners
Gardeners are reporting the insect on a number of edible and decorative plants. Bean family plants are a key target, of course, and this includes wisteria and other landscape specimens. Yellowwood and black locust trees, (both Fabaceae) and fig trees (Ficus) are found hosting at least certain growth stages of kudzu bugs. The bugs are often found clustering on a variety of plants such as fig bushes, magnolia, bronze fennel, but it's unclear whether the bugs are actually feeding.
Kudzu bugs are uniquely irritating to homeowners. As summer ends, kudzu bugs will seek the warmth of your happy home as their winter shelter. They can appear by the hundreds on warm exterior walls, and will look for cracks and entry points to windows, doors, or attics and roof spaces. Those less squeamish may want to just smash the kudzu bugs, but that's not wise. The bugs' fluids smell disgusting, can cause skin irritation, and leave an orange stain on surfaces.
Kudzu bug control
Advice for homeowners will sound familiar to those who already battle Asian ladybeetles, brown marmorated stinkbugs, or boxelder bugs.
- Seal gaps, make doors and windows fit tightly. Check doors, windows, drain penetrations, gable vents.
- Use pyrethroid ("_thrin") sprays on home exterior around doors and windows, soffits, and roof edge.
- Vacuum swarms of bugs on the exterior of houses, then dump them into soapy water, or seal the bag for disposal.
- Do not crush insects that enter the home. Vacuum or scoop up without crushing. Seal the bag, or drown the bugs in soapy water. Smashing these bugs will cause messy stains and foul odor; the insect's fluid can cause skin irritation.
- Eliminating kudzu near the home (Infinitely easier said than done) may reduce the number of bugs on the home.
- Kudzu bugs on garden plants can be knocked into soapy water or killed with garden insecticides.
Beneficial insects like predatory stink bugs have begun to wage war on kudzu bugs. Plans are underway to release an Asian predatory wasp for kudzu bug control. Commercial farmers are urged to seek advice of their local agricultural extension service. Pesticides currently in use have varying effiicacy for control of bean plataspid. The Megacopta Working Group summarizes pesticide advice on a "Soybean Growers" page of their site, KudzuBug.org. An effective management plan considers infestation level and proper timing of pesticide application, in consideration of the treatment's effect on beneficial insects and other crop pests as well.
Gardner, Wayne A., PhD. Megacopta cribraria:A New Invasive Insect Pest Threatening U.S. Agricultural Production and Export Markets
http://www.cotton.org/tech/flow/upload/Megacopta-cribraria-Export-Report.pdf accessed 6-22-13
Kudzu Bug - A Nuisance and Agricultural Pest
http://www.ces.ncsu.edu/depts/ent/notes/Urban/kudzubug.htm accessed 6-22-13
KudzuBug.org - (The Megacopta Working Group) http://www.kudzubug.org accessed 6-22-13
Major Crops Grown in the United States" http://www.epa.gov/agriculture/ag101/cropmajor.html accessed 6-22-13
Roos, Debbie. "Kudzu Bug," NC State University Cooperative Extension http://growingsmallfarms.ces.ncsu.edu/growingsmallfarms-kudzubug/ accessed 6-22-13