The other day we received a question from a reader through the All About Worms Facebook page about a bunch of millipedes that she found on her porch mat. The reader lives in Sacramento, CA, where the weather has been cold and damp recently, and she was wondering what “these little guys” on her porch mat are. Presumably, the reader didn’t know they were millipedes, so we’ve basically already addressed her question, but we’ll flesh out our answer a bit below, explaining why we think she found millipedes and not something else.

First, here is a picture the reader sent of one of the creatures she found:

If you look closely at the bottom half of the creature’s body (in terms of its positioning in the image), you will see tons of small legs, and this is the hallmark of millipedes. Centipedes also have lots of legs, but their legs extend from their bodies, making them longer and more noticeable. The legs of millipedes are generally tucked under their bodies, to the point that they often can’t even be seen. In the picture above, it is quite hard to see the creature’s legs, although they are clearly there. Moreover, millipedes have two pairs of legs on every body segment (except for the first three segments), whereas centipedes only have one pair. This level of detail is hard to discern in the picture above, but if you look really closely, especially at the center of its body, the creature does appear to have two legs per body segment. So, we are very confident our reader found a millipede.

Why our reader suddenly found so many millipedes is unclear. We know that millipedes are commonly found in people’s houses after fluctuations in the weather, and evidently Sacramento has been unusually cold and damp as of late, so perhaps the millipedes were driven to the porch mat for weather-related reasons. (Obviously, the porch is still outside, but the weather still might have driven them there.) The reader also mentioned that all the millipedes are dead, and this too is a bit strange. When millipedes are in foreign environments (again, like homes), they can often dry out and die, but that probably isn’t the case in this instance since the conditions are damp. Perhaps our reader’s porch is covered and therefore dry, and once the millipedes were inside, they couldn’t leave before drying out? Obviously, we don’t know what the exact situation is, but we do know that millipedes that end up in peoples’ houses often dry out and die within a couple of days, which is why finding a few millipedes in your house generally isn’t cause for concern.

So, it is pretty clear that our reader found millipedes, but why she found them where she did, and why they were all dead, is less clear.

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