Asian ladybugs

During the last three years it seemed to me that ladybugs had changed their behavior: In fall, they appeared in large quantities at my window. Some of them got inside (I guess my window is not as sealed as I've always thought), so I had to save them. My rescue operation caused them a bit of a panic which in turn made them secrete tiny bits of a yellowish fluid. When I read up on that, I found out that I wasn't looking at the traditional 7-dot ladybug, but at a new immigrant: The Asian Ladybug. It was imported for fighting vermin. But with its aggressive eating and breeding habits, it is now feared to crowd out native species. Once again: Well done, humanity (see Australia for other “successful” imports of animals and plants). The most interesting thing is that they started appearing in Germany in 2002, so my observations were correct: In fall, they congregate and look for places to hibernate, which causes problems for home owners. But it is not all bad: Apparently, farmers mainly think that their benefits (eating vermin) outweigh their disadvantages (contaminating crops of tender fruits and grapes). From now on, whenever you encounter a ladybird, you can distinguish Asian from European:
Asian: Comes in all kinds of colors, with a varying amount of dots, has a black W on its collar. [Source: Wikipedia]
European: Always 7 dots, always the same color, no W on the collar. [Source: Wikipedia]