|Polished ladybug, a native one|
We all love ladybugs. Some children’s books tell charming little stories about them. Even schoolchildren know that ladybugs eat bad insects. Five states, Delaware, Massachusetts, New Hampshire, Ohio and Tennessee, have chosen these handsome little beetles as their official state insects. Most ladybugs or ladybeetles deserve our esteem. They eat countless numbers of insects that damage our plants, so we are grateful.
What could be bad about ladybugs, or about some of them? It turns out that not all are worthy of our unconditional applause. Some have been brought to this country or to Europe, with the best of intentions, to fight unwanted pests. While they are quite good at this job, sometimes they wear out their welcome.
The first ladybug introduced in North America was the “vedalia” beetle. It was brought from Australia to combat the cottony cushion scale, a nasty insect that was decimating orange groves in California by sucking the plants vital juices. It was a stunning success; the beetle brought the pest under control to the great relief of citrus growers. This species of ladybeetle specializes on cottony cushion scale, which in turn specializes only on plants of the citrus family. So it never became a problem by not going beyond its boundaries. This is not the case with many other introduced insects.
|Infestation of Asian ladybugs in winter|
And this is part of the problem; it is quite capable of eating other ladybugs or to out-compete them by its proficiency. As a result it may be driving some native ladybugs toward extinction. It also can become a nuisance to us because of its inclination to search for warm, comfortable places to spend the winter.
|Convergent ladybeetle, a native one|
It often finds shelter in garages, outbuildings or even our homes. Entire hordes of shelter seeking multicolored ladybeetles may invade our residences much to our annoyance. It seems that the crowds keep getting bigger each year.
|Spotted ladybug, a native one|
We still can’t appreciate the impact of this ladybug on some of the native species and on the ecosystems. But it doesn’t sound good. We continue to observe the development of events rather helplessly. In Europe the multicolored Asian ladybug has been declared a pest. It is too late for that here.
Good bugs gone bad
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