Why are there sometimes swarms of ladybugs?

The lady bugs – or lady beetles – were gathering as the weather cooled down to find a place to overwinter. You might have noticed them clustering by the hundreds or thousands in nooks and crannies inside your house or barn.

You probably encountered the Multicolored Asian Lady Beetle. It was introduced to the U.S. from Asia during the 1970s and 80s to help control crop pests such as aphids. They’re easily recognized because they’re red with black polks-dots.

With few predators and plenty of aphids to eat – the Multicolored Asian Lady Beetle has undergone a population explosion here in the U.S. They’re now in nearly every eastern state – and some western ones.

You should avoid using pesticides on the beetles. They don’t bite or sting – and they won’t reproduce inside your house. If they do come inside, you can just sweep them up – and release them back outdoors.

May 29, 2008

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