"Despite the dubious wisdom of introducing exotic predators without consideration of their impact on native species, around 180 species of Coccinellidae have been intentionally imported to North America for the control of aphids and other pests, and many more have been introduced casually or accidentally. One of the most invasive of these species, Harmonia axyridis, showed up for the first time in Ontario in 1994. These large, extremely variable lady beetles were first recorded as established in the southern United States in 1991, and have been spreading like crazy ever since. Commonly called the Multicoloured Asian Lady Beetle or Southern Lady Beetle, this species can occur in a wide variety of colour forms, but can usually be recognised by a white M-shaped mark on the pronotum (behind the head). Multicoloured Asian Lady Beetles are extremely common, and can become a nuisance when they aggregate in huge numbers in sheltered spots (like your front porch) in preparation to spend the winter. Many lady beetle species spend the winter in dense aggregations of adults, often under leaves or in other natural sheltered area."