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Hold your noses -- the stink bugs are moving indoors

Fortunately, the critters are harmless and won't last long

They seem innocent enough, the slow-moving, reddish-brown bugs that take half an afternoon to cross the room.

You know the ones: You may find one snug as a bug in your towel as you step out of the shower; later you spot another one watching you comb your hair from its perch on a door molding. If you do the right thing and gently escort it to the nearest exit, it repays the favor by emitting a foul-smelling scent.

(Be aware: While you're being a good insect Samaritan, you're probably letting two more in.)

Ah, fall in New England: foliage, pumpkins, and the repeated cry: Mom, there's a stink bug in my room.

"They're everywhere -- upstairs, downstairs, in every room. I just found one in the living room where no one ever goes, and I'm thinking: How did it get there?" said Kathy Siracusa, a Wayland resident who works for the Wayland Board of Health.

"They crack me up because they're so slow. I don't know how they get in -- and we have brand-new windows," Siracusa said.

Leptoglossus occidentalis, or the Western conifer seed bug, a Pacific Northwest species that has been migrating east -- albeit slowly -- for the last 100 years, is such a comfortable house guest that even the family pet may not notice anymore. But don't worry about the buggers: They don't cause any damage, they don't transmit disease, they just want to come in from the cold.

"We get a lot of calls about them this time of year," said Brian Farrell, an entomologist at Harvard University. "They're just looking for places to overwinter."

They're in the family of squash bugs or leaf-footed bugs-- named for the leaflike flattened extensions on their hind legs. Their flashy colored tropical cousins are "giant and glorious," according to Farrell. Fortunately, the local ones grow to only three-quarters of an inch.

Nationwide, there are 88 species of leaf-footed bugs. All of them feed on plants.

From house to house, pet names for the drop-in guests vary from stink bug to squash bug to one of those bugs.

"The Latin names are longer and unpronounceable, but there's no confusion," Farrell said. "The common names are easier, but they're less exact. This is why we invented the Linnaean system."

Like skunks, the bugs use their aroma to fend off predators. Their speed -- or lack of it -- can be a defense mechanism as well.

Quick moves, Farrell said, might attract attention to the bug, "or might make it fall off its plant of choice. They have no reason to hurry."

But don't be fooled by its placid nature. If harassed, it won't bite, because it doesn't have jaws, but it will pierce you with the beak it uses to suck the juices out of pine seeds.

"If you let one walk on you, it won't hurt you," said Farrell. "But if you hold it firmly in your hands, it will stab you with its beak." He described the feeling as that of a pinprick and advised that it's best to pick them up by the tail end of their bodies, even though you may be spritzed in the process.

Their natural winter home is under tree bark or in rock crevices near the evergreens they feed on. So if your house is situated near pine, fir, hemlock or spruce, they may wander inside.

Two other species are also likely to drop in large numbers this time of year -- the familiar lady bug and the Eastern Boxelder, a black insect with red racing stripes. Fortunately, neither one stinks.

"It's not a judgment on how clean you keep your house," said Marion Larson, a biologist with the Massachusetts Division of Fisheries and Wildlife. "They get in through cracks and crannies, even the new houses."

If they do get inside, Farrell said, "they're doomed. Houses are deserts with a couple percent humidity. They just dry out."

At this time of year, Western conifer seed bugs are solitary critters. They're not looking for mates, so you don't need to worry about hosting fetid families.

A wine writer might describe their unique bouquet -- which they emit when scared or squashed -- as a nose of intense bitter apple with hints of underripe banana peel.

"I suppose it's a musky, acrid, sharp, fruity, bitter smell. If bitter could smell," said Farrell.

"Sniff one in cupped hands for the delicate scent of rancid, oily marzipan or moldy almond aroma," a naturalist suggested on a BBC website.

To keep the bugs out, caulk around windows doors and screen attic vents and chimneys. Look for gaps in windows, doors, and screens that can be tightened or somehow closed off from the outside.

Or you can just take Farrell's advice: "Appreciate them. The way they walk. It's sculptural. They're really quite special."

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