It's ladybug time in Tennessee.
Many Middle Tennessee homes are being deluged by hundreds of Harmonia axyridis or multicolored Asian lady beetles. The beetles often gather along windowsills in an attempt to enter homes for hibernation. Once inside they congregate close to windows or light fixtures.
But how did those little buggers became such a nuisance in the past few years?
As the name indicates, the Asian lady beetle, also referred to as the Japanese lady beetle, is not native to North America.
Dr. Charles McGhee, a professor of biology at Middle Tennessee State University, said the U.S. Department of Agriculture (USDA) has attempted several times without much success to introduce the Japanese lady beetle in the United States in the last century.
"We have 475 species of ladybird beetles in North America," McGhee said, adding that those native species do have natural enemies that keep their numbers down.
A newly introduced ladybug, however, works as a biological control to pests such as aphids and other soft-bodied insects that damage North American fruit trees and crops.
An adult ladybug eats up to 250 aphids per day, McGhee said.
In the 1980s, the USDA finally was successful and the Japanese ladybug is now spread throughout the nation.
"In their native countries, they congregate on light-colored rock faces and bluffs in large numbers," McGhee said.
That phenomenon translates into light-colored brick homes in their new country.
But while they can be a nuisance, the Japanese ladybugs - which range in color from a light yellow-orange to a bright red-orange with or without dots - are not considered a pest. On the contrary, they are considered to be a beneficial insect and they are harmless to people: They don't sting, don't damage the homes and don't carry diseases. They only try to find a little protected area to survive the winter.
They also can have a slight odor surrounding them coming from a fluid that they use as protective measure against predators.