Most “worms” found inside a house aren’t worms at all. They’re insect larvae, millipedes, or in rarer cases, actual parasitic worms. The type you’re dealing with depends heavily on where you found it: the bathroom drain, the kitchen pantry, a trash can, a houseplant, or crawling across the floor. Here’s how to identify the most common ones and what to do about each.
Drain Fly Larvae in Bathrooms
Small, dark, worm-like creatures in your shower, bathtub, or sink drain are almost certainly drain fly larvae. The adult flies are tiny (about 1/16 to 3/16 of an inch), fuzzy, moth-like insects that rest on walls near drains. Their larvae live inside the slimy organic buildup that coats the inside of pipes, feeding on soap scum, algae, fungi, and bacteria.
These larvae go through four growth stages over roughly 18 days before turning into pupae, then emerging as adult flies about five days later. Their total lifespan is around 35 days. They strongly prefer drains that don’t get used often, like a guest bathroom shower where water sits stagnant in the trap for weeks. A leak under a slab or in a crawlspace can also create the stagnant moisture they need. If you keep seeing them despite cleaning all your drains, a broken pipe may be the underlying cause.
To confirm which drain is the source, coat the inside of a clear cup with petroleum jelly and place it over the suspected drain overnight. Any adults emerging from the pipe will get stuck. Killing flying adults with sprays doesn’t solve the problem, and no pesticides are registered for use inside drains. The only effective approach is to physically scrub the organic sludge out of the pipe and maintain that cleaning for at least three weeks to break the entire life cycle.
Pantry Moth Larvae in Dry Foods
If you’ve found small whitish or cream-colored caterpillars in your flour, cereal, rice, or spices, you’re looking at pantry moth larvae (most commonly the Indianmeal moth). The adult moths are small and fly erratically around kitchens, but the larvae do all the actual damage to your food.
The telltale sign is webbing. Larvae spin silk threads as they move, so you’ll notice clumped grains, sticky webs in the corners of boxes, or fine threads connecting food particles. You may also spot tiny holes poked through plastic bags, along with small fecal pellets. To check your pantry, pull the inner bags out of cereal and grain boxes and roll them around, looking for clumps or webbing in the creases and corners.
Getting rid of them means discarding all infested food, thoroughly vacuuming pantry shelves (paying attention to cracks and corners), and wiping everything down. Store replacement dry goods in airtight glass or hard plastic containers. The larvae can chew through thin plastic bags, so the original packaging often isn’t enough protection.
Carpet Beetle Larvae on Fabrics
Fuzzy, bristly, slow-moving larvae found near carpets, closets, or upholstered furniture are likely carpet beetle larvae. They look like tiny hairy caterpillars and range from light brown to nearly black depending on the species. Varied carpet beetle larvae have alternating light and dark brown stripes and are wider at the back end. Black carpet beetle larvae are shiny, smooth-looking, and taper toward the rear with a tuft of long hairs at the tip. Full-grown larvae reach about 5/16 of an inch.
These larvae feed on animal-based materials: wool, silk, leather, feathers, fur, and animal hair. They don’t eat synthetic fibers. The damage they cause tends to appear as a large worn area on one section of a carpet or garment, which distinguishes them from clothes moths, whose damage usually shows up as scattered holes. Another clue is the bristly brown cast skins they leave behind when they molt, roughly the size of a grain of salt. Unlike clothes moths, carpet beetle larvae don’t produce webbing.
Thorough vacuuming is the first line of defense, especially along carpet edges, under furniture, and inside closets. Dry cleaning or washing infested clothing in hot water kills larvae. Storing wool and silk items in sealed containers or garment bags helps prevent reinfestation.
Maggots in Trash Cans
White, legless, squirming larvae in or around your garbage can are housefly maggots. Flies seek out warm, protected spaces with rotting organic matter to lay their eggs, and an indoor trash can is ideal. The eggs hatch quickly, the larvae feed on decaying food scraps, and within days they can grow into new adult flies that continue the cycle.
To deal with an active infestation, remove all trash and loose debris from the can. Pouring boiling water down the inside walls kills maggots on contact. A solution of one part vinegar to three parts boiling water does the same while also reducing the odors that attract flies in the first place. After that, scrub the entire interior with hot soapy water and a brush, rinse it out, and let it dry completely before putting new bags in. Going forward, double-bagging food waste and taking trash out more frequently keeps flies from finding a breeding site.
Fungus Gnat Larvae in Houseplant Soil
Tiny, translucent white larvae with shiny black heads living in the soil of your potted plants are fungus gnat larvae. They’re legless and hard to spot unless you look closely at the soil surface. When populations are high, they can leave visible slime trails on the soil that resemble miniature snail tracks.
In small numbers, they’re harmless. But in moist, organically rich potting soil, populations can explode and cause real root damage, particularly in seedlings and young plants. Significant root damage and plant death have been documented in houseplants with heavy infestations. The adult gnats are the tiny black flies you see hovering around your plants. They don’t bite or damage plants directly, but they’re a reliable sign that larvae are in the soil.
The fix is reducing soil moisture. Let the top inch or two of soil dry out between waterings, which kills larvae and makes the environment less attractive to egg-laying adults. Repotting with fresh, well-draining soil helps in severe cases. Yellow sticky traps near the plant catch adults and help you monitor whether the population is declining.
Millipedes and Centipedes
Long, multi-legged creatures found in basements, bathrooms, or crawling across floors are typically millipedes or centipedes. They aren’t worms or larvae. They’re arthropods that hatched from eggs and resemble smaller versions of their adult form at every life stage. But because of their elongated bodies, many people describe them as “worms.”
Both are extremely sensitive to moisture loss, so they’re drawn indoors by damp conditions. Mulch, leaf litter, woodpiles, or paving stones close to your foundation create ideal habitat right next to your home. From there, they enter through cracks in foundation walls, gaps under doors, and openings around windows. Millipedes are slow, curl up when disturbed, and feed on decaying plant material. Centipedes are fast, flat, and actually eat other insects.
Prevention focuses on reducing moisture near your foundation. Pull mulch and woodpiles away from the house, fix leaks near air conditioning units and outdoor faucets, make sure gutters and downspouts direct water away from the structure, and dethatch the lawn to reduce millipede habitat. Sealing entry points with caulk and adding door sweeps or weather stripping to exterior doors and windows keeps them from getting inside.
Pinworms on Household Surfaces
Pinworms are the one type of actual parasitic worm commonly associated with indoor environments. They’re tiny, white, thread-like worms that live in the human intestine and are most common in school-age children. Female pinworms migrate to the anal area at night to lay eggs, which causes intense itching. Scratching transfers the microscopic eggs to fingers, fingernails, and then to surfaces throughout the house.
Pinworm eggs can survive on indoor surfaces for two to three weeks. They cling to toys, faucet handles, bedding, toilet seats, and clothing. Transmission happens when someone touches a contaminated surface and then touches their mouth, or less commonly, when eggs become airborne and are inhaled. The infection is treated with oral medication, but reinfection is common because the eggs are so persistent in the environment. Washing bedding and towels in hot water, frequent handwashing, and keeping fingernails short all help break the transmission cycle.