By Madeline McCurry-Schmidt
When I walk to the bathroom in the middle of the night, I do not want to see this: skittering across the hallway carpet. Yet there it was, a few nights ago, in all its freaky glory. This animal is commonly called a house centipede (Scutigera coleoptrata), and despite my patented lack-of-squeamishness, I hate the thing. It’s like a spider on steroids.
I never saw house centipedes when I lived in California. Apparently, they’re more of a Midwest and Southern thing. Because they can’t close the little holes (called spiracles) in their exoskeletons, they stick to more humid climates so they don’t dry out. They also seem to really like my apartment. Ug!
As they say: know your enemy. So here’s what I’ve learned about house centipedes.
Fact 1: They bleed purple. Squish one of these guys and it leaves a bright purple streak. Purple isn’t really a scary color, it’s just freaky because it’s unexpected.
But it turns out that purple blood isn’t really that unusual. In centipedes and many other arthropods, the blood-like liquid is called hemolymph. Hemolymph is often a grey or greenish. It contains a a protein called hemocyanin, which turns blue when it reacts to oxygen. Hemolymph can also change colors depending on an animal’s diet. Of the California coast, purple hemolymph can be found in sea slugs that eat certain algae.
I can’t find solid information on why house centipedes bleed purple, but multiple studies show changes in hemolymph colors depending on proteins in the hemolymph. A study of several species of butterfly larvae showed that their greenish blood depends on a combination of yellow and blue proteins.
Fact 2: They can have up to 30 legs. Mature house centipedes have 15 pairs of legs. They start out with 4 pairs of legs, but they increase to 15 pairs as they moult. Not only do they have a lot of legs, but their legs have evolved to make them extra freaky. In the picture shown above, you can see how the back legs are longer than the front ones. The millepede’s back legs have actually evolved to look like antennae, which confuses predators.
Fact 3: They live a long time. House centipedes can live from three to seven years. That means the big ol’ centipede in my hallway has definitely lived in my apartment longer than I have…
To be fair, house centipedes are harmless to humans. They actually prey on other arthropods that are household pests. The centipedes in my apartment are hunting insects and spiders. Even though they kill their prey with venom, house centipedes won’t hurt me, so maybe I shouldn’t be so quick to squish them.
And there’s another reason to sympathize with house centipedes.
Fact 4: Reproduction is no fun. The most intimate moment between male and female house centipedes is when they touch antennae. They do this before reproduction to pick up smells from their partners. After the customary antennae-sniffing, the male leaves his sperm on the ground and the female uses it to fertize her eggs.
But then there’s the fact they can lay up to 150 eggs at a time. So maybe I can squish a couple and not feel too bad.