Sowbugs

Color: dark to slate gray
Legs: 7 pair of similar legs
Length: up to about 5/8" long
Antennae: 2 pair (one visible, & one tiny)

Two prominent tail-like appendages which project out from the body on the posterior end allow sowbugs to roll up into a very loose ball when disturbed.

Reduce or elimiminate the moist areas which make their survival possible. For example, remove piles of grass clippings and leaves, store boxes, lumber, firewood, and clover pots off the ground and provide adequate ventilation in crawl spaces.