House centipedes in Winnipeg: the predator in your basement is a symptom

What we're dealing with

The house centipede, Scutigera coleoptrata, is the fast, long-legged arthropod that appears on a basement wall at night and produces more startled phone calls per capita than almost anything else we treat.

The body is 25–38 mm, yellowish-grey with three dark dorsal stripes, but the legs are what people see: fifteen pairs, banded, and much longer than the body, giving the impression of something far larger. The rear pair on a female can be twice the body length.

Centipedes are not insects. They are myriapods — Chilopoda — with one pair of legs per body segment, distinguishing them from millipedes, which have two pairs per segment and are slow, cylindrical detritivores rather than predators.

House centipedes feed on spiders, bed bugs, termites, cockroaches, silverfish, ants and other household arthropods, administering venom by stinging with forcipules — modified front legs rather than true mouthparts. They are mostly nocturnal hunters, and despite well-developed eyes they appear to rely mainly on their antennae when hunting, which are sensitive to both smell and touch.¹

Life stages and cycle length

House centipedes develop by anamorphosis — they hatch with far fewer legs than an adult and add segments and leg pairs at each successive moult until reaching the full fifteen pairs. This is genuinely unusual and it explains why small centipedes look proportionally different rather than simply smaller.

Slow development and long life mean two things for a homeowner. Populations build gradually rather than exploding, so a sudden increase in sightings usually reflects a change in prey availability or moisture rather than a hatch. And because individuals persist for years, a basement that has been damp for a long time can hold a surprising number.

They do not have a seasonal cycle indoors. In a heated Winnipeg basement they are active year-round.

Harborage and hunting

Outdoors, house centipedes prefer to live in cool, damp places.¹ Indoors they take the same conditions:

• Basements and crawl spaces, particularly unfinished ones
• Around floor drains, sump pits and the base of plumbing stacks
• Utility and mechanical rooms
• Behind and beneath stored items on a concrete floor
• Under bathroom fixtures and in the void beneath a tub
• Cracks in fieldstone and cracked parge foundations

They are ambush-and-pursuit hunters rather than web builders or trap setters. They range over surfaces at night, detect prey with their antennae,¹ then close extremely quickly and immobilise it with venom delivered through the forcipules.¹ Larger individuals can capture prey close to their own size.

Because they hunt rather than forage for food scraps, sanitation has almost no direct effect on them. What affects them is moisture and the abundance of other arthropods. That is the whole of it.

They also groom fastidiously, curling around to clean their legs with their forcipules¹ — a detail worth knowing mainly because it is charming, and because it means they contact treated surfaces with their mouthparts as well as their feet.

Solitary hunters

House centipedes are entirely solitary. No colony, no nest, no aggregation pheromone, no cooperative behaviour of any kind. Individuals hunt alone and are aggressive toward one another; cannibalism occurs.

What you are seeing when several appear in the same basement is a shared habitat, not a group. They are there because that space is damp and stocked with prey — the same reason several unrelated spiders end up in the same corner.

This matters operationally in two ways. There is no transfer mechanism, so every individual must contact treatment directly. And there is no central point to eliminate, so control is entirely about making the space unsuitable — which means moisture and prey, not a nest hunt.

Behaviour and speed

House centipedes are among the fastest terrestrial arthropods for their size, and the speed is the reason for the alarm. Their gait is a coordinated wave along fifteen leg pairs, and the pale banding produces a visual blur that makes the animal look larger and more numerous than it is.

C. L. Marlatt, the USDA entomologist, described them in 1902 as darting across floors at great speed, stopping abruptly and remaining motionless before resuming — and noted the alarm this caused among householders.¹ The observation has aged well; it is precisely what people describe on the phone.

They also autotomise — voluntarily shed legs to escape a grip — which is why one found under a shoe often has legs scattered nearby. Lost legs regenerate over subsequent moults.

On the medical question: they can bite defensively if handled, and the forcipules can penetrate human skin, but this is uncommon and the effect is comparable to a minor bee sting with localised pain and swelling. They are not aggressive toward people, are not venomous in any medically significant sense, carry no disease, and damage nothing in the building.

Where in Winnipeg

House centipede distribution in this city tracks basement condition almost perfectly, and it overlaps heavily with the silverfish map — for the obvious reason that one eats the other.

• Older homes with fieldstone or cracked-parge basements, where damp, dark conditions and an insect population coincide. This is the classic setting.
• Properties with seasonal seepage or a high water table, particularly in low-lying areas and near the river corridors, where spring melt raises basement humidity for weeks.
• Unfinished basements with floor drains and sump pits, which provide permanent moisture and a continuous supply of small arthropods.
• Homes with an existing silverfish, spider or cockroach population. The prey comes first; the predator follows.
• Crawl spaces with exposed earth, which are the single most reliable house centipede habitat in any Winnipeg property that has one.

Sightings rise when something disturbs the basement — a renovation, a stored-item clear-out, a sump failure — or when outdoor conditions push individuals inside. In a heated home they are present year-round rather than seasonal.

Natural control factors

• Prey availability. The dominant factor without close competition. Reduce the silverfish, spiders and small insects and the centipede population declines with no other intervention.
• Humidity. They require damp conditions and desiccate in dry air. The same dehumidification that suppresses silverfish suppresses centipedes twice over — directly, and by removing their food.
• Cannibalism and territorial aggression. Real, and it limits density.
• Predation. Limited indoors. Domestic cats catch them occasionally, to no population effect.

DIY: what works, what backfires

Our treatment process

1. Inspect for the prey population first. This is the actual diagnosis. We look for silverfish, spiders, small cockroaches and other arthropods, because that is what is sustaining them.
2. Moisture assessment of basements, crawl spaces and utility areas — readings, seepage points, condensation, drainage faults.
3. Crack-and-crevice treatment of harbourage in basements, crawl spaces and utility rooms, targeting where they shelter during the day.
4. Perimeter and entry-point application at grade level, to intercept individuals moving in from outdoors.
5. Address the prey population, which is very often a separate silverfish or spider treatment. We will quote that separately and explain why it is the durable half.
6. Written moisture and ventilation advice, which does more here than any product.
7. Return visit on request, though with a slow-developing predator the meaningful measure is whether the basement has dried out.

We will tell you plainly when the centipedes are not the problem. If a basement is reading 80% humidity and full of silverfish, treating centipedes is billing you for the wrong job.

The chemistry, and how it kills

There is no bait for centipedes. They eat live arthropods, so there is nothing to poison and nothing carried back to a nest. Control is contact-based and environmental, which is why placement and moisture matter far more than product choice.

Worth noting the same physical limitation that applies to spiders: a centipede's body is held well clear of the surface on fifteen pairs of long legs, so contact with a treated floor is limited. Dusts in the cracks they actually shelter in outperform surface sprays.

Treatment timeline

Physiology and recent thinking

An ancient predator

Centipedes are among the oldest terrestrial predators in the fossil record, with the class Chilopoda extending back to the Silurian — they were hunting on land before insects had wings, and long before vertebrates left the water. Scutigera coleoptrata belongs to the Scutigeromorpha, the group with the compound-like faceted eyes and the long legs, and is the most visually acute centipede lineage.

The forcipules themselves are a striking piece of evolutionary engineering: the first pair of walking legs, modified into venom-injecting claws.¹ No insect has anything equivalent — it is a limb repurposed as a fang.

The sensory question

Despite having developed eyes, house centipedes seem to rely mostly on their antennae when hunting, which are sensitive to both smell and touch.¹ That is an interesting tension in an animal that also has the best eyes in its class — and it suggests the eyes may serve predator avoidance and light detection more than prey capture.

Where the research attention actually sits

Centipede venom has attracted genuine pharmacological interest, because chilopod venoms are chemically distinct from spider and scorpion venoms and contain peptides with unusual ion channel activity. That work focuses on larger tropical species rather than Scutigera, but it is the direction the field is moving.

The framing that should change

The more useful research position — and one that better reflects the biology — is to treat house centipede abundance as an indicator rather than a target. Given their prey range across spiders, bed bugs, cockroaches, silverfish and ants,¹ centipede density in a building is a reasonable proxy for total indoor arthropod abundance. Nobody appears to have formally tested that, but it matches what we find on site.

Cultural history

Marlatt, 1902. The USDA entomologist C. L. Marlatt — the same author who wrote the early circular on silverfish — produced a brief and vivid description of the house centipede that has been quoted ever since. He recorded their habit of darting across floors, freezing motionless, then resuming, and observed that they occasionally moved directly toward householders, causing considerable consternation.¹ The period detail is dated; the behavioural observation is not.

The hundred-legger. "Centipede" means hundred-footed, from Latin, and it is wrong for essentially every species. Scutigera has thirty legs. No centipede has exactly a hundred, and the leg count is always an odd number of pairs — a genuine developmental constraint, meaning a hundred-legged centipede is not merely rare but impossible.

Global folklore. Centipedes carry a heavier symbolic load in cultures where large venomous species occur — appearing in Japanese legend as the ōmukade, a giant centipede slain by the archer Fujiwara no Hidesato, and in various traditions as a symbol of persistence or menace. North American folklore around house centipedes is comparatively thin, amounting mostly to the shared experience of being startled by one.

The reputation problem. House centipedes are among the most beneficial arthropods that occur in homes and among the most disliked, and the gap between those two facts is unusually wide. The animal eating your silverfish is the animal you most want removed.

The internet era. House centipedes have a genuine online following — a durable genre of "actually they're good, don't kill them" posts, complete with people naming the one living behind their washing machine. That is a more accurate cultural position than the animal has ever previously enjoyed, and it is roughly the advice we would give.

References

1. Scutigera coleoptrata — prey range, venom delivery via forcipules, nocturnal hunting and antennal reliance, leg grooming behaviour, outdoor habitat preference, and C. L. Marlatt's 1902 USDA description. species reference
2. Marlatt, C.L. (1902). Contemporary USDA Division of Entomology descriptions of household arthropods, including the house centipede and the silverfish. Referenced in UF/IFAS Extension EENY-705. edis.ifas.ufl.edu (PDF)

This article carries fewer references than others in this library. House centipedes attract very little research funding because they cause no damage and no disease, and we would rather show a short honest reference list than pad it with sources that do not say anything.