Asian Lady Bug

Harmonia axyridis is a large coccinellid beetle. Its color ranges from yellow-orange to black, and the number of spots between 0 and 22. It is native to eastern Asia, but has been introduced to North America and Europe to control aphids and scale insects. It is now common, well known and spreading in those regions.

It is commonly known in North America as Asian lady beetle, or Japanese ladybug, and in the United Kingdom as the Harlequin ladybird (the latter because it occurs in numerous color forms). It is also known in North America as the multicolored Asian lady beetle, and (because it invades homes in October in preparation for hibernation) as Halloween lady beetle.

When the species first arrived in the UK, it was labeled "the many-named ladybird", because among the names listed were: multivariate, southern, Japanese, and pumpkin ladybird.Harmonia axyridis is a "typical" coccinellid beetle in shape and structure, being domed and having a "smooth" transition between its elytra (wing coverings), pronotum and head. It occurs in three main color forms: red or orange with black spots; black with four red spots; and black with two red spots. However, numerous intermediate and divergent forms have also been recorded.

This species was possibly established in North America as the result of introductions into the United States in an attempt to control the spread of aphids. Whatever the source, in the last two decades, this insect has spread throughout the United States and Canada and has been a prominent factor in controlling aphid populations.

In the U.S., the first attempts to introduce it took place as far back as 1916. Repeated efforts were not successful. In the early 1980s, aphids were causing significant problems for growers of pecan trees, so the United States Department of Agriculture again attempted to bring the insect into the country—this time in the southeastern United States, using beetles brought from their native region in northeastern Asia. After a period of time, USDA scientists concluded that their attempts had been unsuccessful. However, a population of beetles was observed near New Orleans, Louisiana around 1988, though this may have been an accidental introduction event independent of the original, planned efforts. In the following years it quickly spread to other states, being occasionally observed in the Midwest within 5–7 years, and becoming common in the region by about 2000. The species was also established in the northwest by 1991, and the northeast by 1994, in the former case quite possibly involving additional introductions, rather than reaching there from the southeast. It is reported that it has heavily fed on soybean aphids (which recently appeared in the U.S. after coming from China), supposedly saving farmers vast sums of money in 2001.

Asian Ladybugs hibernate in cooler months, though they will wake up and move around whenever the temperature reaches about 50°F. Because the beetles will use crevices and other cool, dry, confined spaces to hibernate, significant numbers may congregate inside walls if given a large enough opening.

These beetles use pheromones to "call" each other, allowing for the large gatherings that are often seen in the Autumn.

They often congregate in sunlit areas because of the heat available, so even on fairly cold winter days, some of the hibernating beetles will “wake up” because of solar heating. These large populations can be problematic because they can form swarms and linger in an area for a long time. These beetles can form groups that tend to stay in upper corners of windows. This beetle has been also found to be attracted to dark screening material for its warmth. This beetle has good eyesight, and will come back from where it was removed, and is known to produce a small bite if provoked.

Asian Ladybugs, like other lady beetles or ladybirds, uses isopropyl methoxy pyrazine as a defensive chemical to deter predation, but also contains this chemical in its hemolymph at much higher concentrations than many other such species. These insects will “reflex bleed” when agitated, releasing hemolymph from their legs. The liquid has a foul odor (similar to that of dead leaves) and can cause stains. Some people have allergic reactions, including allergic rhinoconjunctivitis when exposed to these beetles. Sometimes, the beetles will bite humans, presumably in an attempt to acquire salt, although many people feel a pricking sensation as a lady beetle walks across the skin. Bites normally do no more harm than cause irritation although a small number of people are allergic to bites.