Why are there so many ladybugs and lady beetles around Wisconsin this fall?

If you've ventured outdoors recently, you might have noticed an unusual amount of ladybugs — or perhaps insects that appear to be ladybugs but differ in a few subtle ways.

As temperatures start to drop, Coccinellidae — the insect family of small beetles that includes ladybugs — are once again swarming the state. Wisconsin sees dozens of species of small beetles this time of year, including ladybugs, but one is particularly prevalent: the multicolored Asian lady beetle, according to P.J. Liesch, director of the UW-Madison Insect Diagnostic Lab.

"The [Asian lady beetles] are the ones that folks are really seeing a lot of at the moment," Liesch said. "Those particularly beetles are very active, flying around and coming to structures because they're looking for sheltered wintering spots."

While the beetles are generally harmless, Liesch added, there are a few steps you can take to protect your home to ensure they don't take shelter in your house for the winter.

Here's what to know about Asian lady beetles and why they're all over Wisconsin this fall.

What are lady beetles, and how are they different from ladybugs?

Though they belong to the same family of insect, multicolored Asian lady beetles are different from ladybugs in a few key ways.

Unlike distinctly red ladybugs, these beetles are more orange or black. In fact, the insects get the "multicolored" part of their name from the wide variation in their color, ranging from orange with no spots, orange with spots or almost fully black, Liesch said. The beetles also have a white-colored neck region with a distinct black, M-shaped pattern.

As for the second part of its name, the lady beetles are actually native to East Asia, not Wisconsin or the U.S., Liesch said. For about a century, the U.S. attempted to deliberately introduce the beetle to the country's environment to control other insect populations.

"That didn't seem to work, until, all of a sudden about 40 years ago, some populations of this insect caught on, and it has now spread around much of the U.S.," he said.

Why are there so many ladybugs and lady beetles in Wisconsin right now?

While you might feel like the beetles have appeared out of nowhere, they're actually around all year — but they become a lot more noticeable in the fall, when they start swarming buildings and houses to look for winter hibernation spots.

In their native East Asian habitats, the insects hibernate through the winter in the nooks and crannies of natural structures like cliffs, Liesch. As winter approaches, the beetles are looking for similar spaces in order to survive the cold.

"When you think about modern homes and buildings and other structures... in the way we have siding and things like that, there's no shortage of vertical and horizontal linear features," he said, "so they're basically mistaking it for their natural overwintering habitat in rock faces and cliffs."

As for how long they'll stick around, Liesch said Wisconsin usually sees peak activity of lady beetles and ladybugs from mid to late October. However, if warmer temperatures persist in southern Wisconsin, expect them to flutter around a bit longer before the cold weather suppresses them.

Can ladybugs and lady beetles hurt humans?

Though these beetles rarely bite, they do often protect themselves through a process known as "reflex bleeding." This is when the bug will release a slightly orange, odorous liquid called "hemolymph" onto their predators.

If humans are exposed to large amounts of this liquid, especially if they are crushing the bugs by hand, Liesch said that can lead to adverse symptoms. Pets, too, can become ill if they ingest a lot of hemolymph from beetles — but both of these cases are also fairly rare.

"In my mind, rather than a health threat, I think of them indoors as mostly a nuisance," Liesch added.

Otherwise, lady beetles and ladybugs can actually help out your garden by eating up aphids, the small and sap-sucking insects that can kill off plants.

How to manage a ladybug infestation

If you're facing a ladybug or lady beetle infestation, here are a few tips to protect your home:

• As a preemptive step, seal up your home so insects cannot get inside in the first place. This includes using caulk, insulation foam or backer rods to close any gaps in your foundation, windows or door frames.

• As another preemptive step, which may be easier than physically sealing gaps around your house, spray pyrethroid insecticides around any openings into the home. These sprays are found at most hardware stores and can kill off bugs before they make their way inside.

• If the ladybugs do get inside, sweeping or vacuuming them up is perhaps the easiest way to dispose of the insects.

• Build  or buy a light trap to attract ladybugs using an LED, blue or UV light. Once they're trapped, they can safely be released outside.

• Spray the colony with soapy water or leave a bowl of soapy water near a light source where the ladybugs gather.

Claire Reid contributed to this report.

This article originally appeared on Milwaukee Journal Sentinel: Why are there so many ladybugs, lady beetles swarming Wisconsin?