The hundred-legged one

House Centipede

What is it about invertebrates that creeps people out so much? Cockroaches are the stereotype of unclean dwellings, and used dramatically to draw shivers from an audience, but really the insects probably have little to no interest in you personally. A spider crawling out of a drainpipe can prevent someone from stepping into a bathtub (no way was I climing in until it was taken outside or flushed down again), but the chances of it crawling on you, much less biting you, are pretty slim.

My personal insect-phobia, the one that will cause me to throw a garment into the air shrieking should I discover one hiding inside a seam, is earwigs. Creep. Me. Out. I’m not sure why, although perhaps it goes back to my childhood and having earwigs occasionally climb into clothing while it was drying on the line outside (I should note I was never bitten by one, but that didn’t reduce their creepiness). They particularly favoured the lining of bathing suits, for some reason. I’m also not terribly fond of silverfish, though that doesn’t have any childhood encounters tied to it. The rest of the groups I’m generally okay with, although spiders are better if they’re at a distance.

One guy I know revealed that he’s creeped out by leeches. Another guy said his was house centipedes, which was also my sister’s when I asked her. A couple days ago we had one of these show up in our bathroom sink (the photos in this post are of this obliging individual). I have to admit they’re fairly creepy crawlies, as creepy-crawlies go. Up to two inches long, with giant long legs that spread out in a large oval shape, long antennae and rear legs, and they can dash across a wall at lightning speed. They’ve never really bothered me, but perhaps that’s because I have all of my energy invested in earwigs.

House Centipede

Centipedes, unsurprisingly, get their name from their many legs (cent = hundred, pedes = feet). Millipedes also take their name from their many feet, but the “milli” means thousand. You can tell the difference between centipedes and millipedes because the former are usually flattened with just one pair of legs per body segment, while millipedes are rounded and have two pairs of legs per body segment. Millipedes have a defence mechanism of curling up into a spiral when threatened, while centipedes, which don’t have the same strong upperside, instead run away (and I challenge you to try catching one!).

There are a number of different species of centipedes in North America, but the house centipede (Scutigera coleoptrata) is the only one from the order Scutigeromorpha (the group is also called house centipedes; since the North American species is the only one on the continent, it can get away with using the group name as the species’ common name). It’s actually not even native to North America, but was instead originally from the Mediterranean and has since spread (hitching rides with humans or their cargo). It can now be found here as well as in Europe and Asia, and a few spots in Africa, Australia and New Zealand. In Japan, they’re reasonably popular and Wikipedia suggests it can often be found for sale in pet shops.

House Centipede

Millipedes are scavengers, eating detritus and dead material. Centipedes, including the house centipede, are predators, eating insects and arthropods commonly found in a household environment, such as spiders, ants, silverfish, cockroaches, termites and bedbugs, and as such could be considered beneficial bugs to have around. They kill their prey by injecting venom through small “fangs”, the same way spiders do. Although it is technically possible to be bitten by a house centipede, you would have to be intentionally or accidentally handling it, and even then it probably wouldn’t feel like much, as their fangs are too small to puncture most skin. The biggest house centipedes might be able to inflict a good bite if presented some soft skin, which would feel a bit like being stung by a bee, and would similarly subside after a few hours (also, a small number of people may be allergic to the centipede’s venom like some people are to bee stings).

Although they can be found almost anywhere in the house, they prefer damp locations, such as basements or bathrooms, or overwatered houseplants. Outside they can be encountered under rocks, in wood piles or in compost heaps. They’ll happily overwinter in your house, and are commonly seen in spring (or in mild spells mid-winter) when the weather begins to warm.

House Centipede

House centipedes start out with just four pairs of legs when they hatch, but go through a series of larval stages (“instars”) where they shed their previous exoskeleton (their hard outer shell – insects wear their skeleton on the outside and attach all their muscles to its inner surface, compared to vertebrate animals whose skeleton is inside with the muscles affixed to the outside). It may take them up to three years to reach full size, where they’ll have 15 pairs of legs (centipedes can have anywhere from 15 to 100+ pairs of legs, but the number of legs is always odd). Once full grown they can live up to seven years.

Adults have compound eyes, like many insects (though we tend to think of flies first), and so have excellent vision (also helpful, in addition to their speed, in evading capture). They’re the only group of centipedes to have this feature. They have three modified feeding appendages, “toothed” mandibles (visible in the above photo as a sort of beak-like shape under the face), a pair of maxillae, and a pair of leg-like palps (visible in the previous photo as . The mandibles “chew” the prey while the other two appendages manipulate it. The “fangs” are found on the first body segment, behind the head. I kind of think it looks like a grasshopper head, and if you couldn’t see the rest of the body you might almost believe it was related to this much less creepy crawlie group.