Multicolored Asian Lady Beetle

Description:

(Mystery solved ... see Comments, Notes) What am I looking at? It's been below freezing at night most of this week. It warmed up a little last night and was shirt-sleeve weather today ... when many, many ladybugs arrived. Most looked like the first photo, but there was a lot of variation in color, size of spots, no spots. Are they all the same kind of ladybug? Where did they come from all of a sudden? All these photos taken within 10 minutes in a 6-foot radius.

Habitat:

Arrived at the house in a swarm to hibernate for the winter.

Notes:

Color variation:
http://iowabuglife.blogspot.com/2011/10/...

Bug Guide:
http://bugguide.net/node/view/397

From Wikipedia:

Other common names: Harlequin ladybird, because it occurs in numerous colour forms. And because it invades homes in October in preparation for overwintering, as Halloween lady beetle.

This species is widely considered to be one of the world’s most invasive insects, partly due to their tendency to overwinter indoors and the unpleasant odor and stain left by their bodily fluid when frightened or squashed, as well as their tendency to bite humans. In Europe it is currently increasing to the detriment of indigenous species, its voracious appetite enabling it to outcompete and even eat other ladybirds. The harlequin ladybird is also highly resistant to diseases that affect other ladybird species and carries microsporidian parasite to which it is immune but that can infect and kill other species. Native ladybird species have experienced often dramatic declines in abundance in areas invaded by H. axyridis.

A useful informal clue for distinguishing this species from most other Coccinellidae is that the pronotum of the succinea colour forms of Harmonia axyridis has white markings that typically define an "M"-shaped black area, as seen on a beetle resting head-upwards (or "W"-shaped if it is head-down). They always have reddish-brown legs ...

In the United States, coccinellids usually begin to appear indoors in the autumn when they leave their summer feeding sites in fields, forests, and yards and search out places to spend the winter. Typically, when temperatures warm to the mid-60s F (around 18°C) in the late afternoon, following a period of cooler weather, they will swarm onto or into buildings illuminated by the sun. Swarms of coccinellids fly to buildings in September through November depending on location and weather conditions. Homes or other buildings near fields or woods are particularly prone to infestation. (This swarm came Dec. 1, a warm day after a cold snap, to a house in a rural area near the woods. Check.)

From Encyclopedia of Life:

The Asian ladybird beetle 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. The wide geographical spread of this insect is cause for concern in some places, as it is a threat to native species and biodiversity, can damage crops (especially grapes) and migrates into houses in the fall, becoming a household pest.