“There are hundreds of them,” my friends in Belfast told me last week. “Thousands.”

They pointed to several tiny buglike silhouettes meandering across the living room window and in the curtains.

“Ladybugs. Everywhere,” they said. “We keep sweeping and vacuuming them up everywhere.”

A multicolored Asian lady beetle (Harmonia axyridis) in Searsport last summer. Photo courtesy of Ian Stevenson, via GBIF

At my house in Troy, I haven’t had a ladybug scare, the worst winter bug problem having been an infestation of whiteflies in the plants. But from what I can gather, huge winter congregations of a particular species of ladybugs inside the house are not unusual occurrences in these parts.

Just to be clear, ladybugs are not bugs. They’re beetles. “Bug” is a technical term in entomology, so the creatures we all call ladybugs are known to entomologists as ladybird beetles.

The ladybug in question is the multicolored Asian lady beetle, scientific name Harmonia axyridis. It was introduced in parts of the United States in the 1990s because it eats crop-battering aphids and scale insects. Another ladybug, Coccinella septempunctata, or seven-spot ladybird beetle, was introduced in Maine in the early 1970s for the same purpose.


Both species did a pretty good job on the aphids — in fact, H. axyridis may have done too good a job — but they also spelled invasive disaster for local species of ladybugs. In a talk about aphid control for the Maine Entomological Society a few years ago, University of Maine entomologist Andrei Alyokhin explained that as the introduced populations of seven-spot ladybirds rose sharply in the 1980s and ’90s, Maine’s native ladybugs, such as Coccinella transversoguttata (transverse lady beetle) and Hippodamia tredecimpunctata (thirteen-spot lady beetle), declined in population. Counts indicate that in the early 1970s, the transverse lady beetle was by far the most common ladybug in Maine. Thirty years later, they had all but disappeared, displaced by H. axyridis and C. septempunctata.

The multicolored Asian lady beetle population soared largely because the beetle has no natural predators here to keep its numbers balanced. Ladybug counts indicate we have about the same numbers of ladybugs as 50 years ago, but most of them are the invasive species instead of the ones we saw often as kids.

Beetle expert Bob Nelson of Clinton tells me he sweeps thousands of multicolored Asian lady beetle carcasses out of his barn every year.

My brother Al, who lives in Gray and kills bugs for a living, told me infestations are usually the result of the ladybugs looking for a warm place to spend the winter.

“Usually they cluster in a big ball,” he said, “and the best time to treat for that is in September or October.”

But, he said, “most times I tell them (the inquirers) to just wait it out and usually they (the ladybugs) end up dying.”


The only way to do anything about them is to try to stop them from coming in, but “there’s no real good way to deter them from entering the house.”

Luckily, as most of us learned when we were kids, ladybugs are pretty much harmless. They can wreck the taste of your wine if they get into the grape-crushing process, but mainly they’re just a nuisance, and possibly unnerving in large numbers.

In Al’s expert opinion: “They’re cute but can be a pain … Lol.”

Dana Wilde lives in Troy. You can contact him at dwilde.naturalist@gmail.com. His book “Winter: Notes and Numina from the Maine Woods” is available from North Country Press. Backyard Naturalist appears the second and fourth Thursdays each month.

Only subscribers are eligible to post comments. Please subscribe or login first for digital access. Here’s why.

Use the form below to reset your password. When you've submitted your account email, we will send an email with a reset code.

filed under: