Most “long bugs” people encounter fall into a handful of common species: house centipedes, silverfish, earwigs, stick insects, and longhorned beetles. Each has a distinctly elongated body plan, but they differ in leg count, habitat, and whether they pose any concern. Here’s how to tell them apart and what to do if they’re showing up indoors.
House Centipedes
The house centipede is probably the most startling long bug you’ll find inside. The body itself is only one to one and a half inches, but adult females have a rear pair of legs nearly twice their body length. Factor in all 15 pairs of legs plus antennae, and the whole animal looks three to four inches long. The body is yellowish with three dark stripes running lengthwise, and the legs are banded light and dark, giving them a wispy, almost alien appearance as they sprint across walls.
House centipedes are born with just four pairs of legs and add more with each molt, passing through stages of 5, 7, 9, 11, and 13 pairs before reaching the adolescent stage at 15 pairs. They’re predators that eat spiders, cockroaches, and other small insects, so seeing one usually means there’s a food source nearby. They prefer damp, dark spaces like basements and bathrooms.
All centipede species are technically venomous, but house centipedes are classified as “fast but delicate” and rarely bite. When centipede bites do occur across all species, they typically cause only local reactions that resolve within hours to a few days. For context, research published in the World Journal of Neurology noted it would take the venom from roughly 1,000 centipede venom glands to produce a fatal dose in an average adult. A house centipede in your bathroom is not a medical concern.
Earwigs
Earwigs are dark brown, flat, and roughly half an inch to an inch long, with a distinctive pair of curved pincers (called cerci) at the tail end. Those pincers look menacing, but earwigs are not poisonous and generally won’t bite or sting. They can pinch your skin with the forceps if handled, though it rarely breaks the surface. Earwigs are nocturnal and attracted to moisture, often turning up under flowerpots, in mulch beds, or in damp laundry rooms.
Silverfish
Silverfish are teardrop-shaped, silver-gray, and about half an inch to three-quarters of an inch long. They move with a distinctive fish-like wriggle. Three thread-like tails fan out from the rear, and two long antennae extend from the head, making them appear longer than they are. They feed on starchy materials like book bindings, wallpaper paste, and cardboard. Like earwigs and centipedes, they thrive in humid environments and are most active at night.
Stick Insects
If you’re curious about the longest bugs in the world, stick insects hold the record by a wide margin. The longest species ever measured is Chan’s megastick from the rainforests of Borneo: the record specimen had a body length of 14 inches and measured 22.3 inches with legs outstretched. A close relative, another Bornean species, reached 12.9 inches in body length and 21.5 inches total.
Stick insects achieve their extreme length through a survival strategy called masquerade crypsis. They don’t just blend into the background like camouflaged animals. They physically resemble twigs, bark, lichen, or leaves so convincingly that predators look right past them. This disguise is so central to their survival that it shapes nearly everything about their biology. Flightless species, locked into their twig impersonation, have evolved to eat a wide variety of plants since they can’t easily travel to find a preferred host. Females of many species simply drop their eggs from wherever they’re perched rather than moving to a specific site, because moving would blow their cover.
You won’t find these giant species outside of tropical forests, but smaller native walking sticks (typically 3 to 4 inches) do show up in gardens across North America.
Longhorned Beetles
Longhorned beetles get their name from antennae that run the majority of their body length, sometimes exceeding it. Their bodies range from half an inch to over two inches depending on the species, but those sweeping antennae can make them look dramatically longer. They’re typically found on or near trees, since their larvae bore into wood. A few species, like the Asian longhorned beetle, are considered serious invasive pests that damage hardwood trees. If you find one indoors, it likely came in on firewood or through an open window.
Why Long Bugs Show Up Indoors
Nearly every elongated bug that turns up in your home is there for moisture. House centipedes, silverfish, and earwigs all need humid environments to survive, and a damp basement or bathroom is an invitation. The EPA recommends keeping indoor humidity between 30 and 50 percent, and no higher than 60 percent. A basic dehumidifier in your basement or crawl space is the single most effective step.
Beyond humidity control, a few structural changes make a real difference. In dirt-floor basements and crawl spaces, install ventilation (either fan-driven or passive vents with quarter-inch hardware cloth to keep out rodents) and lay thick plastic sheeting over the soil as a vapor barrier, sealing seams with specialized tape. Insulating basement walls buffers temperature swings and reduces condensation. Check for cracked or poorly connected pipes in kitchens, bathrooms, and utility rooms. Pipe insulation reduces condensation on cold-water lines, and drip pans should be emptied regularly.
The exterior of your home matters too. Create a three-to-six-foot gap between plants and the house. Replace mulch borders directly against the foundation with vegetation-free zones: 18-to-36-inch strips of crushed stone with no plantings. Make sure rainwater drains away from the foundation, gutters are clear and properly sized, and downspouts direct water well away from the house. In attics, ensure proper cross-ventilation through windows on opposite sides, soffit vents, or ridge vents. Even window sills pitched incorrectly or weep holes that have been filled with caulk can create enough trapped moisture to attract pests.
These changes won’t just deter one type of long bug. They make your home less hospitable to the entire category of moisture-loving arthropods, from centipedes to silverfish to earwigs, all at once.