Why You’re Being Invaded by Ladybugs

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From the hills of southern Appalachia to the Canadian border, there is a bizarre invasion conquering the land.  Not the invasion of a foreign army with legions of militant soldiers, but swarms of tiny beetles, complete with red backs and black spots, affectionately known as ladybugs.

Across the nation these otherwise cute and harmless creatures are being spotted blanketing the sides of vehicles, penetrating the interiors of homes and swarming in large mass throughout residential areas.

We turned to the University of Kentucky’s College of Food & Environment for answers and quickly realized there was a lot we still had to learn about these creatures we all remember from our childhood.

For starters, the ladybugs you’re seeing today are probably not the same ones you remember from your childhood: Though ladybugs are native to North America, in 1916 wildlife officials attempted to establish a non-native species of ladybugs, the Asian Ladybeetle (Harmonia axyridis) which they believed would be more effective in controlling aphid populations.

Initially, this Asian species was believed to have failed in establishing a population on the North American continent; however, in 1988, some seventy-years later, a population of the Asian beetles was observed in the wild near New Orleans, Louisiana.  Many scientists believe this particular species of ladybugs were unintentionally released into the country via a contaminated freighter at the port of New Orleans.

In the years that followed, the population of the Asian ladybeetles quickly spread to other states and even succeeded in driving out native ladybugs.

According to the University of Kentucky, large numbers of ladybugs infesting homes and buildings in the United States were first reported in the early 1990s, on the heels of the Asian ladybeetle outbreak.

By 1992 the Asian Ladybeetle was working to establish a population in central Appalachia and since then, each year around late-October ever growing swarms of these Asian ladybugs can be spotted infesting homes and buildings in the United States in an attempt to secure an overwintering site indoors.

“As autumn approaches, the adult beetles leave their summer feeding sites in yards, fields and forests for protected places to spend the winter. Unfortunately, homes and buildings are one such location. Swarms of lady beetles typically fly to buildings in September though November depending on locale and weather conditions. In [Central Appalachia], most migration to buildings occurs in October. Beetle flights are heaviest on sunny days following a period of cooler weather, when temperatures return to at least the mid-60s. Consequently, most flight activity occurs in the afternoon and may vary in intensity from one day to the next… Once inside they crawl about on windows, walls, attics, etc., often emitting a noxious odor and yellowish staining fluid before dying,” states the university.

Their proximity to October 31 has given these Asian beetles a unique name, “The Halloween Ladybugs”.

Scientists at UK say Asian lady beetles generally do not injure humans and are mainly a nuisance. Unlike some household pests (e.g., fleas and cockroaches), they do not reproduce indoors — those appearing in late winter/early spring are the same individuals that entered the previous fall. Lady beetles do not attack wood, food or clothing.

Although Asian lady beetles do not transmit diseases per se, recent studies suggest that infestations can cause allergies in some individuals, ranging from eye irritation to asthma.

“Asian lady beetles are also becoming a concern of the wine industry. Due to their noxious odor, even small numbers of beetles inadvertently processed along with grapes can taint the flavor of wine.”

Residents wishing to remove ladybugs from their homes are encouraged to vacuum them; however, most agree that the greatest way to curb their entry is to ensure that all areas of the home are properly sealed so that there are no entry points for them to infiltrate.

Though the autumn swarms of the Asian ladybugs are a severe nuisance for many, scientists typically agree that the Asian invasion of the beetle is largely a blessing, as their diet primarily consists of aphids which destroy forests and soybeans.  This particular species of ladybugs are believed to have saved American farmers vast sums of money.

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