Some may be other arthropods. One of these is the millipede. You can tell millipedes are not insects. They have too many legs. All true insects have six legs.
Millipedes have four per body segment and they have lots of body segments.
Millipedes are long worm-like, slow moving and curl up when disturbed. They are an annoyance though when they get in a house. If you must kill them, spray or dust Sevin in a six-foot wide band around the house, or pull mulch back from the house and treat this area. The idea is to kill enough of them to lessen the numbers getting inside. Other pests entering the house can be slowed down by using a perimeter spray around the house.