Asian lady beetle

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iAsian lady beetle

Secure

Scientific classification

Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Coleoptera
Family:	Coccinellidae
Genus:	Harmonia
Species:	H. axyridis

Binomial name

Harmonia axyridis
Pallas, 1773

Male on top

H. axyridis

The Asian lady beetle (Harmonia axyridis), often known as the multicolored Asian lady beetle, and harlequin lady beetle, because of the species' tendency to vary in color from orange to yellow to even black, or halloween lady beetle because it invades homes in October in preparation for hibernation, is now a common insect in North America. It is a non-native insect on the continent, possibly established 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 has been a prominent factor in controlling aphid populations. However, many people are now coming to view the Asian lady beetle as a nuisance, probably partly due to the fact that they like to overwinter indoors, along with the fact that they emit an unpleasant odor and a stain when squashed. It is also currently increasing in Europe to the detriment of indigenous species, due to its voracious appetite which enables them to out-compete and even eat other lady beetles, as it also does in the United States. The ladybug has also shown to be a minor pest of tender fruits and grapes in Iowa, Ohio, New York, and Ontario, and native ladybug species have experienced often dramatic declines in abudance in areas invaded by H. axyridis. Despite the troubles the Asian lady beetle causes, many farmers still view the bug as a beneficial insect. It is reported that the beetle 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 lady beetles hibernate in cooler months, though they will wake up and move around whenever the temperature reaches about 50°F (10°C). 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. 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. Also, the bugs do not understand that glass cannot be penetrated by their small bodies, so many of the bugs will repeatedly crash into window panes.

The Asian lady beetle, like other lady beetles, uses isopropyl methoxy pyrazine as a defensive chemical to deter predation, but the Asian lady beetle contains this chemical in its hemolymph at much higher concentrations than many other lady beetle 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. It is believed that some people have allergic reactions when repeatedly exposed to lady beetles (especially dead ones). 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 are believed to do no more harm than cause irritation although some people are evidently allergic to bites.

These beetles can sometimes be difficult to identify because of their variations in color, spot size, and spot count. The easiest way to identify an Asian lady beetle is to look at the pronotum and see if the black markings look like a letter “W” or “M” (depending on if the marking is viewed from the front or the back).

1 Introduction
2 Control
3 References
4 External links

[edit] Introduction

In the U.S., the first attempts to introduce the beetle 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, the beetle quickly spread to other states, being occasionally observed in the Midwest within about 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.

This species has begun penetrating the UK; first seen in 2004. It has now had confirmed sightings from the South East to the Midlands. This is of particular concern as the harlequin ladybird has the potential to jeopardise the native species due to it being a very effective aphid predator. When this food source becomes scarce, it will eat ladybird eggs and larvae, and butterfly/moth eggs and caterpillars.

Allergies to the beetle have been confirmed by Dr. Kusum Sharma and colleagues from the University of Louisville.^[1]

[edit] Control

These beetles have the ability to squeeze through the smallest of openings, even through a closed window. Although some consumers have reported positively on the effectiveness of spraying with products such as Spectracide Bug Stop, the only way to fully prevent a home invasion is to tape the windows shut so they cannot get through these cracks. Others suggest tolerating the insects as long as the invasion is relatively mild or using a vacuum cleaner to remove the pests with less mess.