Pill Bugs are more closely related to shrimp and crayfish than to insects. They are the only crustaceans that have adopted to living their entire life on land. Pill bugs have no posterior appendages and can roll up into a tight ball when disturbed which is where they get their nickname, "Roly-Poly." They live in moist environments outdoors but occasionally end up in buildings. Although they sometimes enter in large numbers, they do not bite, sting, or transmit diseases, nor do they infest food, clothing, or wood. They range in size from ¼ to ½ inch long and are dark to slate gray since they require moisture; they do not survive indoors for more than a few days unless they are in very moist or damp conditions.