1. They don’t really have a thousand legs. Millipedes are sometimes called “thousand-leggers,” while the similar centipedes are called “hundred-leggers.” Millipedes actually have two pairs of legs per body segment. They add body segments, and legs, as they grow, so most adults end up with 30 to 90 pairs, but one species has over 300 pairs of legs.
2. Millipedes are not even insects. If you paid attention to #1 above and you remember anything from biology class, you would already know that. Adult insects have 3 pairs of legs, totaling 6. Fully-grown millipedes have way more, but just to confuse the issue, newborn millipedes have only 3 pairs of legs. They add more with their very first molt. Like insects, millipedes are arthropods but they belong in the Class Diplopoda.
3. Lots of legs, but alas, no speed. Even with all those legs, millipedes move very slowly and methodically (it takes a while for each of those legs to move forward in turn). They don’t need to move quickly because they are vegetarians so they don’t need to capture prey. When threatened themselves, they have a couple of defensive tricks (see #4 and #5) to keep predators away.
4. They don’t bite or sting, but they do stink. Well, they don’t always stink but some do have special glands on their sides that can emit a foul-smelling fluid to repel enemies. The fluid is said to contain hydrocyanic acid, iodine, and quinone. If you pick up a millipede, you may get a whiff of that smell but be careful because the fluid can cause small blisters on the skin of some people.
5. Millipedes can roll themselves up. When threatened or disturbed, millipedes can also roll up into a protective coil, centipedes can’t do this.
6. They can migrate in large numbers. Millipedes need damp conditions to keep them moist and to supply the rotting vegetation that they feed on. If their environs get too dry, or even too wet, they will hit the road looking for better conditions. When a lot of millipedes do this all at once (often in the fall), it can be impressive, especially if they end up in your downstairs laundry room.
7. Millipedes actually don’t like your house much. An occasional millipede can end up inside your home, or lots of millipedes can end up inside when conditions change outside, and if you have gaps around doors that let them in. The drier indoor air usually kills them fairly soon unless they find a very damp area such as a laundry room or crawlspace to hide in for a while. They don’t reproduce indoors.
8. The way you manage your lawn affects millipedes. Millipedes live in heavy mulch and leaves, and love a lawn with a dense thatch layer beneath the grass surface. Dethatching lawns and taking steps to allow grass to dry out (mowing shorter and watering early in the day) discourages the moisture-loving millipedes.

For more, see:

• Why Are There Millipedes in My House?
• Where Are Those Millipedes Coming From?

Photo Credit : By Josch13 – pixabay, CC0, Link