Ladybugs: helpful, sometimes pesky

October 2, 2005

By Madeline Bodin

Who loves a ladybug? Until recently, everyone did. These tiny beetles
gobble aphids and other soft-bodied insects that plague crops and
ornamental plants.

It is said that their name refers to the Virgin Mary, to whom our
European ancestors gave thanks for the beetles that saved their crops.
They are also called lady beetles. In Britain, they are called
ladybirds or ladybird beetles. For centuries, they were thought of as
bearers of good luck. In Iran, they are called "good news." As far as
we know, the name has nothing to do with feminine characteristics.
There are, indeed, gentleman ladybugs. Ladybugs share a basic body plan
with their fellow beetles, which includes the wings that let them "fly
away home." It's the hard forewings that give a ladybug its shell-like
covering. The large, membranous hindwings underneath unfold and are
used for flying.

The high-water mark for ladybug love may very well have been in 1977,
when the New Hampshire Legislature named the two-spotted ladybug as
that state's official insect. (Massachusetts, Ohio and Tennessee had
already made ladybugs their state insects.) In 1989, New York
designated the widespread and common nine-spotted ladybug as its state
insect.

There are some 450 native species of ladybug in North America and
several thousand species in the world. New Hampshire has about 60
native species within its borders, and Vermont has about 40. Almost
every one of those species is a beneficial insect, eating plant pests
that we might otherwise use chemicals to kill.

But sometime in the 1990s, the worm, or maybe in this case the larva,
began to turn. (Ladybug larvae are spiky-looking things, often equal in
size to mom and dad.) Ladybugs have always overwintered as adults in
large groups, sometimes even in people's houses.

As the 1990s went on, more and more people in the eastern, mid-western,
and northwestern United States were complaining about hundreds or
thousands of ladybugs entering their homes in the fall.

While the two-spotted, native ladybug had always done this to some
extent, the new culprit was the multicolored Asian lady beetle
(Harmonia axyridis), also known as the Halloween ladybug. This ladybug
is a tree-dweller, originally from Asia, and it comes in a variety of
shades, from yellow to orange to red.

This ladybug had been intentionally released time and again - in
Georgia, Ohio and Washington - throughout the 1970s as a natural
predator of crop pests. When few of these ladybugs were recaptured, it
was thought they were dying out. Instead, they had just flown away to
new homes. The good news is that these ladybugs did such a number on
the pecan aphids in Georgia that chemical pesticides are no longer used
for aphids there. The bad news is that every fall, Halloween ladybugs
find their way into American homes, sometimes in horror-movie-like
numbers.

Ladybugs don't eat while inside your house, and they don't reproduce
there. They are just seeking a warm place for the winter, which may be
a small solace when you find one doing the backstroke in your coffee.

The bugs can be kept out by tightly sealing your house, including
putting screens over all roof, attic and wall vents. If they are
already inside, ladybugs can be sucked up with a vacuum cleaner that
has a nylon stocking inserted into the extension wand. The ladybugs
that get in your house are usually non-native and, quite obviously,
overabundant, so do with them what you will.

Just don't crush them. They stain. And don't eat them.

"They taste horrible, which is part of their natural defense and why
many of them are brightly colored - an example of aposomatic
(warning) coloration," says John Weaver, who, as an entomologist with
the New Hampshire Department of Agriculture, I trust did not arrive at
this knowledge through his own experience.

He says that wine makers have found that when Halloween ladybugs get
harvested with the grapes, the crushed beetles taste so bad that they
can ruin the wine.

We won't be rid of the Halloween ladybug any time soon, but we may have
learned our lesson. Weaver reports that "the U.S. Department of
Agriculture seems to have adopted new guidelines in selecting lady
beetles for introduction, selecting species that are specialized
predators and not selecting species that are generalized predators."

Introduced ladybug species don't just bug humans. They have an impact
on other ladybugs as well. New York hasn't seen its state insect -
the nine-spotted - in years.

It's believed that a different introduced species, the seven-spotted
ladybug, may have done it in either by eating it or by out competing
it.

It's a little harder to love a ladybug these days, but it's a little
harder to be one, too.

END