One of our readers recently asked us, “Are these thin black worms with lots of legs good for my plants?” She either forgot to include a picture or didn’t take one, so we will attempt to answer her question without referring to a photo.

We suspect she might be talking about millipedes. While millipedes aren’t technically worms (they are arthropods) they do have thin, long, worm-like bodies. Their length and color vary depending on what species they are, but all millipedes have segmented bodies and two pairs of jointed legs per segment. Here is a picture of a millipede from Wikimedia:

Millipedes are often confused with centipedes, which are also arthropods. Millipedes and centipedes both have thin, segmented bodies with many legs. However, millipedes are typically rounder, like the creature in the photo, and have two pairs of jointed legs per segment. Centipedes have flatter bodies, and only have one pair of jointed legs per segment. Also, millipedes are more often black or dark brown, and centipedes are lighter colored. Therefore, we think our reader is probably dealing with millipedes, not centipedes.