Asian Lady Beetles
By Beth He
In recent years, the introduction of Asian lady beetles (Harmonia axyridis) has sparked concerns, as these seemingly harmless insects have caused severe ecological problems. These beetles are often confused with ladybugs because of their similar features. They are also small, oval, and convex but are usually orange or yellow. They also have black spots on their back—around 19 of them. Ladybugs, in contrast, are bright red and have around 11 black spots. Another way to tell the two apart is based on the markings behind their head. Asian lady beetles have a black ‘M’ or ‘W’ along with larger white spots in this area as opposed to ladybugs, which do not have this black marking (Boggs and Jones). The life of these beetles consists of four stages, including egg, larva, pupa, and adult. On average, it takes about 3-6 weeks for an egg to fully develop and mature. Once they are adults, they can live for more than a year. Asian lady beetles’ diet primarily consists of aphids and other similar-sized pests (“Multicolored Asian Lady Beetle”). Understanding their distinctive features and characteristics sets the stage to explore their environmental impacts.
Asian lady beetles are native to Asia, originating from countries such as China, Russia, Korea, and Japan. There, they naturally lived in trees and fields (Potter, Michael F., et al). Although non-native, these beetles have spread to and caused significant damage in North America. In the past, they were purposefully brought from Asian countries to North America as a part of a USDA program aiming to control tree pests. This was due to the fact that native species, such as ladybugs, were not as effective in controlling aphids, a tree pest. Additionally, there are also records of these beetles being unintentionally transported by ships to ports in New Orleans and Seattle (Boggs and Jones). Within the past 30 years, Asian lady beetles have now been found abundantly in the U.S. along with South America, Europe, and Africa. As a result, they are now classified as a global invasive species.
Infestation is a major problem regarding Asian lady beetles. As the weather cools down, they will often flock from natural habitats to houses and buildings to spend the winter. Therefore, structures near forests or fields are at a higher risk. Furthermore, they are attracted towards buildings with light-dark contrast and those facing southwest, as they will receive afternoon sunlight. Additionally, the beetles will release a strong odor and secrete compounds when disturbed. This secretion is usually yellowish and stains surfaces (Potter, Michael F., et al). Because of the odor and stain, it is better to use a vacuum to remove them instead of crushing them or using ‘bug zapper’ traps. To prevent these beetles from entering buildings, it is advised to seal all gaps, install insect screens, and if needed, use an insecticide (Boggs and Jones). In order to mitigate the damage caused by Asian lady beetles, education about identifying them, proper removal methods, and preventative measures must be implemented.
Works Cited
Boggs, Joe, and Susan C. Jones. "Multicolored Asian Lady Beetle." Ohioline, Ohio State University Extension, ohioline.osu.edu/factsheet/ENT-44.
"Multicolored Asian Lady Beetle." UC Statewide IPM Program (UC IPM), ipm.ucanr.edu/natural-enemies/multicolored-asian-lady-beetle/.
Potter, Michael F., et al. "Asian Lady Beetle Infestation of Structures." University of Kentucky Department of Entomology, entomology.ca.uky.edu/ef416.
