Recent rain events coupled with decreasing temperatures are shaking things up outside. This is the time of year when insects and other arthropods that normally make their homes outside, start to move around and look for shelter. The critter that is causing the most calls so far is the millipede; which is an arthropod, but not an insect. Millipedes are helpful decomposers when outside and feed on decaying organic matter. They are commonly confused with centipedes, which are predaceous.
The millipedes we see moving indoors are general small and dark brown with rounded bodies (Figure 1). Millipedes have two pairs of legs per body segment, while centipedes only have one pair per segment. Millipedes are completely harmless to people – they do not bite, pinch, or otherwise cause injury.
Figure 1. (Right) Millipedes submitted by a Minnehaha County client.
The best defense against millipedes is to make sure all doors, windows, and other entry points into the home or structure are well-sealed. Outside, make sure that leaf litter and mulch are away from the foundation. Millipedes need a humid environment to survive, so if they are entering a damp basement a dehumidifier will help make the area less hospitable.
Many people ask about using pesticides to solve their millipede invasion, but the root cause of the issue is that they are coming in from outside. Pesticides will only kill the millipedes that come into direct contact with the product. It is more effort, but finding their entry point(s) and closing them off is the only way to stop them from getting inside. This will also help prevent other insects and arthropods from finding the same way in. Dead millipedes can be vacuumed or swept up and disposed of in the trash.
- Cranshaw, W. Millipedes, centipedes and sowbugs.
- Hahn, J. and Ascerno, M. Sowbugs, millipedes, and centipedes.