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Ladybugs,
also called lady beetles or ladybird beetles, are actually
beetles in the Coleoptera family Coccinellidae. As insects go,
they are a very beneficial group, being natural enemies of many
insects, especially aphids and other critters that damage plants
by feeding on their sap. A single ladybug can consume vast
quantities of aphids in its lifetime, perhaps as many as 5,000
or more. There is a brisk business in commercial ladybugs for
aphid control, and some of the species found here in North
America are actually "invasives" brought from Europe or Asia for
such purpose. Coccinella septempunctata, the seven-spotted
ladybug, sometimes called ‘C-7', is a medium-sized, orange
beetle with seven black spots. It is a European species that was
introduced into the US to aid in managing some aphid pests.
Harmonia axyridis, the Multicolored Asian lady beetle, was
introduced to North America many times, finally taking hold and
becoming established in the 1980's. This invasive has become far
and away the most numerous of the Coccinellids here in the
midwest, and they are becoming one of the most annoying insect
pests, invading homes to overwinter, much as the box elder bug.
Adult ladybugs have convex, hemispherical shaped elytra (the
hardened wings used to cover the soft flying wings underneath)
that can be yellow, pink, orange, red, or black, and usually are
marked with distinct spots. This is a type of warning coloration
(aposematic coloring), thought to discourage predators. Lady
beetles also have another defense: an odorous, noxious fluid
that seeps out of their leg joints when the insects are
disturbed. I can truthfully say, I've been fooling with ladybugs
since I was a child but I've never noticed such a thing. It
must be that the quantity of such fluid is so small as to affect
only small creatures.
Ladybugs, both adults and larvae, are well-known primarily as
predators of aphids (plant lice), but they prey also on many
other pests such as soft-scale insects, mealybugs, spider mites
and eggs of the Colorado Potato Beetle and European Corn Borer.
A few feed on plant and pollen mildews. One larva will eat about
400 medium-size aphids during its development to the pupal
stage. An adult will eat about 300 medium-size aphids before it
lays eggs.
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