And there's not much you can do about it!
The recent warm, damp evenings have been very good for millipede migration. These hard-shelled, elongated, "thousand-legged" arthropods spend their lives under mulch, rocks and other debris where they provide a valuable ecological service as "recyclers."
Then the weather turns just right and the millipedes start to migrate, often traversing long distances to end up under the garage door, in the basement, thick on the road, on the side of the building, etc., etc., etc. You get the picture. Once they start wandering they've got nowhere to go and all night to get there.
During the nocturnal wanderings some will accidentally enter the house and garage. They usually die within a day after getting inside because the house is much too dry for them to survive. They always coil up into a spiral when they die or when they are handled.
Spraying is of little benefit. They will die within a few hours anyway and sprays do not kill quickly nor do they repel the millipedes while they are wandering. The practical solution is to sweep them up and discard.
More about accidental invader millipedes is on our website.
Millipedes have 4 legs (2 pairs) on each body segment.