Harmonia axyridis is a large coccinellid beetle originally native to eastern Asia, but which 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 as Harlequin ladybird in the United Kingdom.
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 (known as form succinea); black with four red spots (form spectabilis); and black with two red spots (form conspicua). However, numerous intermediate and divergent forms have also been recorded. The species is typically large (7–8 mm long) and even more dome-shaped than native European species (these characteristics distinguish Harmonia axyridis from native species in the UK). It often has white markings (typically defining an "M"- or "W"-shaped black area) on its pronotum, and usually brown or reddish legs.
Biology and behaviorEdit
Harlequin Ladybirds hibernate in cooler months, though they will wake up and move around whenever the temperature reaches about 10 °C (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 eye sight, and will come back from where it was removed, and is known to produce a small bite if provoked.
These beetles can sometimes be difficult to identify because of the variations in color, spot size, and spot count of the elytra. The easiest way to identify an Harlequin Ladybird 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).