Megacopta cribraria is the species of nuisance pest more commonly referred to as the kudzu bug, the bean plataspid, lablab bug, and globular stink bug. Since kudzu and soybean plants are its two main hosts, the kudzu bug has gained considerable notoriety for the economic problems it causes. However, its initial discovery was as a nuisance to homeowners; in October of 2009, it was first noticed in the United States in nine northeast Georgia counties as large aggregations of insects flying from patches of kudzu onto the outside walls of nearby houses and structures. A year later, the insect was confirmed to be present in more than 60 north and central Georgia counties as well as limited distributions in North and South Carolina. It is believed that the kudzu bug will continue to spread into most areas where kudzu, an invasive vine that grows unimpeded throughout the southeastern U.S., is established. To see if you reside in or around a county known to be infested with the kudzu bug, see the current distribution map.
The kudzu bug is getting a reputation as a nuisance to homeowners and those wishing to enjoy the outdoors at two times each year: early spring (March) and the fall (mid-October through late November).
The first peak of activity occurs in the early spring when the kudzu bugs emerge from winter inactivity in search of kudzu, their preferred host plant. As spring progresses and kudzu continues to grow, the bugs become less troublesome for the homeowner, and fewer and fewer numbers will be sighted on vehicles and in landscapes. However, the kudzu bug is not gone for good; it's feeding and reproducing in kudzu, and thus a new generation, or cycle, of the kudzu bug begins. In June and July, adults produced in this new generation are thought to move over to soybean plants, and during these months, the kudzu bug may become a nuisance to soybean growers as well as home gardeners and organic farmers growing various types of beans.
The second peak of nuisance activity occurs in the fall. Based on what is known about other insects, a combination of day length, change in kudzu physiology, dying host plants, and declining temperatures is thought to be responsible for the second peak of nuisance activity occurring in the fall. In recent years, the kudzu bugs' migration from host plants to overwintering sites has consistently began in mid-October and persisted until late November or early December.
As stated above, kudzu bugs are inactive during the winter months, and seek overwintering sites in the fall. These sites include any crack or crevice where a group of bugs can aggregate. Gaps under the bark of trees, gaps under the siding of homes, and high places (such as the fascia boards and gutters on the edges of homes) are only a few examples of overwintering sites. Kudzu bugs are also attracted to light-colored surfaces, especially the color white: the white siding of a house, a white car, a white shirt, etc. Even though kudzu bugs only reproduce on plants known as legumes, it is not uncommon to find them on most types of vegetation when large numbers are present, including oak and pine trees, tomato plants, azaleas, etc.---plants that are clearly not hosts.
Aside from being seemingly everywhere in the fall, kudzu bugs possess a few other traits that make them a particular nuisance. When a person is exposed to the kudzu bug, an allergic reaction may occur, resulting in staining of the skin and skin irritation (as pictured below). Additionally, the bugs may invade the house if it is not properly sealed. It is important to remember here that kudzu bugs belong to the same superfamily as stink bugs and have been known to emit an unpleasant odor that can be hard to get out of your nose, your furniture, your carpet, etc. Crushing the bugs thus becomes a problem, as they emit an unpleasant odor and may stain the surface they are crushed upon.
Kudzu bugs are less active during the cool mornings of the fall, but when the sun comes out and the temperatures warm, their flying and nuisance activity increases dramatically. Those planning outdoor activities should take this observation into account and try to plan their activities for the morning rather than the afternoon.
Suggested measures for ensuring that the house is properly sealed against kudzu bugs should be taken in late summer and are as follows:
In the event that kudzu bugs are able to enter the home, it is important to bear in mind that they should not be crushed; a crushed kudzu bug may leave stains on indoor surfaces as well as odors that may prove difficult to eliminate. Rather, they should be vacuumed, and once bagged, placed in hot, soapy water. It is best to avoid using a vacuum that will push them through the motor since they can produce foul smells, the resulting 'bug goo' can leave stains, and some people may have an allergic reaction if they come in contact with the ground bug parts. A stocking or pantyhose placed in the vacuum tube and secured to the end of the tube with a rubber band can help by catching the insects before they reach the motor of the vacuum.
As a second line of defense, the homeowner may seek to gain relief from the invading insects landing on the exterior of his or her home. This can be accomplished with an exterior wall application of an insecticide spray labeled for nuisance insect control outdoors. Unfortunately, re-application(s) may be necessary, especially when nearby kudzu remains as a source of re-infestation. To reduce the frequency of re-application, long-lasting formulations such as microencapsulated and wettable powder products should be used if possible. When using insecticide-based products, always read and follow the directions for use on the product label. As a general rule, indoor insecticide use for control of the kudzu bug is discouraged; however, a pyrethroid insecticide can be used to directly spray bugs landing on the outside of a building.
The control of the kudzu bug on structures may prove frustrating for homeowners and pest management professionals alike. The overwhelming numbers of insects combined with nearby source(s) of re-infestation can make sustained control difficult. Ultimately, the elimination of the kudzu bug relies on the physical removal or death of kudzu via herbicide, so if possible, the homeowner should try to remove nearby kudzu in the summer.