Lost Ladybugs was originally published in the BFEC Newsletter, Vol. 16/No. 4, Fall 2012.
"Lost ladybugs" you ask? With masses of them congregating in any indoor crevice in the fall, this certainly doesn't seem to be the case. The invaders, which are actually beetles, can bight and emit a foul smelling and staining liquid when disturbed. But these are not the ladybugs of our youth. They are Asian multi-colored ladybugs (Harmonia axyridis), which were likely introduced in the 1980s as a biological control for aphids.
While they have been reported to help control aphids on soybeans crops, they also contaminate fruit crops and they have likely caused the marked decline of native ladybug species (which are also aphid predators), outcompeting them with higher birth rates and tolerance of cold temperatures.
As its name implies, the Asian multi-colored ladybug varies in color and number of spots. Distinguishing them from the hundreds of native species is tricky, but look for a black "W" or "M" (depending on your view) just behind the head.