One formerly widespread species, the nine-spotted ladybug, is now virtually extinct in northeast North America

One of the great mysteries of the insect world right now ranking up there with the loss of winged pollinators in general is what has happened to North America's native ladybug species? About 20 years ago, they started to "fly away" just like the nursery rhyme. There are still ladybugs to be found; but, the chances are they are not native ladybugs. Invasive ladybird beetles now account for two-thirds of all ladybugs in the United States and Canada. Other countries are faring no better. The UK is suffering a serious invasion of Harlequin ladybugs. These aliens are taking over and pushing out the native species there as well. Many more countries are fighting their own battle with invasive alien ladybird beetles.

Source:
http://pippap.hubpages.com/hub/Where-Have-All-The-Ladybugs-Gone