The children's rhyme says "Ladybug, ladybug, fly away home," but many residents of southwestern Pennsylvania are responding with "Not in my home," after an invasion of the tiny orange and black-spotted insects earlier this week.

	The Asian lady beetle was introduced to Pennsylvania in 1978 and 1981 to control aphids.

The Carnegie Museum of Natural History has logged dozens of calls from homeowners who have found unwelcome clusters of the bugs dotting their interior walls, crawling around south- or west-facing windows or flying through their homes.

The ladybugs -- more properly multicolored Asian lady beetles -- are just doing what comes naturally in an unnatural and foreign environment: looking for a place safe from winter's icy breath.

"They're trying to find a place to over-winter and can slip in through the tiniest of cracks to find some shelter and warmth," said Chen Young, an associate curator at the museum.

The round to slightly oval-shaped Asian lady beetles are less than a quarter-inch in diameter, can be yellow to red in color but most often are orange, and are speckled with as many as 19 black spots on their concave wing covers. The head is usually concealed beneath a disk-shaped "collar," which is cream to yellow in color with a black "M" design in the center.

A native of eastern Asia, the beetle was introduced into the United States in the late 1970s by the U.S. Department of Agriculture to control aphids, voracious feeders that were damaging Southern crops, like pecans and soybeans.

The Asian ladybugs were introduced in Pennsylvania in 1978 and again in 1981, but colonies failed to take hold. The first over-wintering adult Asian lady beetles were observed in the state in 1993, according to Steven Jacobs, extension entomologist in Penn State University's College of Agricultural Sciences.

"In the last several years, multicolored Asian lady beetles have caused quite a stir," Jacobs said. "But the growth in numbers in Pennsylvania and other states probably came not from those earlier USDA releases but from an accidental release of beetles from an Asian freighter in New Orleans."

Indigenous ladybugs, thought to be sources of luck in many rural areas of the state, possibly because of their aphid appetites, are slightly smaller. They're also suffering because of the foreign competition.

When the weather turns cold, the Asian lady beetles abandon the woods, brush and gardens where they have spent the warm weather months chowing down on aphids, scale insects and other pests. They then are attracted to the warmth and sunlight reflecting off south- and west-facing windows and walls of houses.

"In their native lands, they would be flying to the rock cliffs that are south-facing and therefore retain more heat," Jacobs said. "There they spend the winter in cracks and crevices, protected from the cold."

The ladybugs don't hibernate, but rather spend the cold weather months inactive, in a reduced metabolic state.

When they find a suitable spot, they send out pheromones, not as a sexual attractant but to alert other ladybugs, male and female, to the spot they've found. That's why they are seen massing in the late fall but not during the summer.

The best place for them in houses is in unheated attics or garages, between the exterior walls and insulation or against window frames.

"Inside houses are actually not a great place for them to over-winter because it can actually get too warm for them and they begin to move around," Jacobs said. "But they only have so much fat reserve which they quickly burn up and then die."

Although the late fall massing of the ladybugs this year is drawing more attention than in previous years, it's not because there are more of them but because conditions are right.

"The whole thing is triggered by cold nights, a frost, and then days when the temperature gets up to 60 or 70 degrees," Jacobs said. "The warmer temperatures allow them to fly. If it gets up to 60 degrees again this weekend, you'll probably see more."

After the warm weather ends, the beetles will go dormant and won't be seen by homeowners until spring, when they'll emerge from their indoor hiding spots in search of exits.

Even though Asian lady beetles can be a nuisance, homeowners should refrain from using pesticides to get rid of them. They are generally harmless. Although they have pincher jaws and can bite, they do not carry venom or human diseases, and do not feed on wood, clothing or food.

Closing up cracks and holes is the best way to keep ladybugs from getting into buildings. That includes sealing around windows, doors, siding, pipes and utility lines, chimneys and other openings with silicone or silicone-latex caulk, and replacing or repairing damaged screens on windows and storm doors. Attic fans, fireplace chimneys and exhaust vents should be covered with fine mesh screening.

If they have already moved in for the winter, Jacobs recommends carefully sweeping them up with a broom and dust pan. Try not to crush them, as their blood leaves a reddish stain that is hard to remove from paint, wallpaper and fabrics.

"Because they're very beneficial in controlling damaging pests," he said, "they should be released unharmed in a protected area outside."