It's quite common. Helpful critters can often become pests. It seems to be true when few and not many want them around. Especially if you are an aphid, garden pest, or snake who relies on other's misfortunes for sustenance. It happens all the time, but when it happens in your community, in your school, home or back yard, it's much more troublesome.
Some people think they are kind of cute.
Others pay no attention. Either way, swarms of ladybugs are back again this year. Some claim they are only looking for a warm winter home and to improve conditions in the community. This could be. I've seem more ladybugs in the last few months than I've ever seen in my entire life.