The Asian lady beetle (Harmonia axyridisis) is often mistaken for the American ladybug which is indigenous to the United States. The Asian lady beetle was introduced into America in 1988 to aid in the assistance of reducing aphid populations. They have since spread throughout North America, taking over the habitat of the native American ladybug populations to become the dominant species. Both the Asian lady beetle and American ladybug are of the family Coccinellidae which are found worldwide and consist of over 6,000 species.
Asian Lady Beetle Bites
Asian lady beetles are not only destructive to plant life but they also have an aggressive nature and are prone to biting (hard enough to break the skin) when moved or disturbed. Asian lady beetles are classified as nuisance pests that can invade homes and businesses in large numbers during the winter season.
Identify of Asian Lady Beetles VS Ladybugs
Both the Asian lady beetle and the American ladybug are similar in appearance and patterns of behavior. While it can be difficult for the untrained eye to tell the difference between the two species, there are a couple of ways that you can tell them apart if you look closely enough. The Asian lady beetle has a very distinctive white “W” shape on the area immediately behind the head called the pronotum and the color of the dome is typically reddish orange, tan or yellow with black spots. The American ladybug has a shiny black pronotum with two small white circles and a dome that is a bright scarlet red with black spots.
Asian Lady Beetle Diet
The natural prey of the lady beetle is aphids but they will also feed on mealy bugs, spider mites, leaf beetles, moths and weevils and occasionally on pollen and nectar. Lady beetles are also known for their cannibalistic behavior, as they will consume lady beetle larvae when normal food sources become difficult to find.
Habitat, Overwintering & Reproduction of the Asian Lady Beetle
Asian lady beetles prefer temperate climates to breed, and are prolific in the spring and early fall. A single female is capable of laying as many as 3,800 eggs in one season typically in batches of 20 to 30 eggs each day. The lifespan of an adult lady beetle is anywhere from three months to three years, depending on the temperature. As the winter months approach, they will migrate to the sides of buildings seeking areas of warmth especially surfaces that are white or light colored. They will also swarm inside houses to protect themselves from the cold winter weather. While the Asian lady beetle prefers cool, dry places during the winter months but will become active in temperatures that exceed 50 degrees Fahrenheit. They prefer to congregate in larger groups where they summon their own kind with pheromones. They will gather in sunny areas in large numbers to warm themselves including window panes and outside walls often returning to the same location even after being removed.
Defense & Odor of Asian Lady Beetles
The Asian lady beetle will secrete an unpleasant odor from their legs as a form of defense when threatened or attacked. This highly concentrated orange colored chemical can be especially foul smelling when the bug is crushed. The chemical can stain the materials that it comes in contact with such as curtains, carpets and clothing.
Asian Lady Beetles & Health Concerns
Unlike American lady bugs, Asian lady beetles are well known for their aggressive natures. Although the bite is not poisonous it can cause an allergic reaction which can result in allergic conjunctivitis (pink eye). Proteins from the chemicals that are released when the lady bug is threatened along with droppings and body parts may become airborne causing allergic reactions in the form of allergic rhinitis (inflammation of the membrane inside the nose), chronic cough, asthma, and urticaria (hives) in those individuals who are susceptible. Since Asian ladybugs are typically found in homes from September through March they are considered seasonal allergies, much like pollen.