The kudzu bug (Megacopta cribraria) is a major invasive species in North America. This insect is technically a true bug, not a beetle or a typical stink bug, and is the sole representative of its family (Plataspidae) in the United States. Its ability to rapidly colonize new areas and feed on economically significant crops has established it as a significant agricultural and residential pest.
Identifying the Kudzu Bug and Its Invasive History
The adult kudzu bug is easily recognizable by its small, shield-shaped, or globular body, measuring between 3.5 and 6 millimeters in length. Its coloration is typically mottled, ranging from olive-green to various shades of brown and black. The body’s shape is distinctive because a large, rounded dorsal plate, called the scutellum, covers the wings and abdomen, giving it a blunt rear end.
While mature adults are dark, the immature stages, or nymphs, can appear paler, sometimes exhibiting shades of light brown or pale orange. The insect originated in Asia, specifically India and China, where it is a known pest of legume crops. It was first detected in the Western Hemisphere near Atlanta, Georgia, in 2009, likely arriving via international shipping containers.
Following its initial discovery, the kudzu bug spread rapidly throughout the southeastern United States, establishing itself in over a dozen states within a few years. Its strong flying ability and association with the widespread kudzu vine allowed it to quickly traverse large geographical distances.
Life Cycle and Primary Food Sources
The kudzu bug typically produces multiple generations each year, a life cycle known as bivoltine in the United States. Adults emerge from overwintering sites in the spring to feed and lay eggs on host plants, primarily the kudzu vine and certain other legumes. Females deposit their small, oval eggs in two characteristic side-by-side rows, typically on the undersides of leaves.
Newly hatched nymphs must consume specialized capsules of endosymbiotic bacteria that the female deposits beneath the eggs. This unique biological requirement is necessary for the bug to successfully digest nutrients from its host plants. Nymphs progress through five distinct growth stages, or instars, before developing into adults, a process that takes approximately six to eight weeks during warm weather.
The kudzu bug possesses piercing-sucking mouthparts, which it uses to tap directly into the plant’s vascular system, specifically the phloem. By extracting phloem sap, the bug drains the plant of moisture and nutrients, causing stress. While kudzu serves as a major reservoir for the first generation, the second generation often moves into economically important legume crops, especially soybeans, to feed and reproduce.
Agricultural Damage and Home Nuisance
The feeding activity of the kudzu bug causes significant damage to agricultural fields, particularly soybeans, which is one of its preferred hosts. By sucking sap from stems and petioles, the bugs reduce the plant’s overall vigor, leading to nutrient loss and water stress. Untreated infestations have been documented to cause soybean yield losses ranging from 18% to over 47% in the early years of its invasion.
Apart from the economic impact, the kudzu bug is a severe residential nuisance, especially in the fall. As temperatures drop, adult kudzu bugs aggregate in massive numbers on the sunny, light-colored sides of buildings as they search for sheltered overwintering sites. They are particularly attracted to highly reflective surfaces, such as white or tan walls.
When disturbed, the insects employ a defensive mechanism common to many true bugs by releasing a foul-smelling chemical. This odor can be pungent and highly unpleasant when bugs are crushed or vacuumed up. The defensive fluid can also leave a temporary yellow-orange stain on interior surfaces, clothing, or skin.