Millipedes do not bite or sting humans. They are usually found in the garden and in decaying vegetation. Some millipedes secrete a liquid that leaves a stain and causes severe skin inflamation and blindness in humans.
Millipedes normally live outdoors where they feed on damp and decaying wood and vegetation. Sometimes they leave the soil and can be found crawling in the house, or hiding beneath flower pots. The migration into the house may be due to heavy rain which raises the water level in the soil and forces them to seek shelter elsewhere.
When threatened or in danger, they roll up into a ball. Some species secrete a repugnant liquid which is brown or white. The liquid is toxic to other small animals and is usually exuded slowly, although sometimes it can discharge the liquid as a spray.