Blow flys lay eggs on animal carcases, meat, fish, animal excrement and decaying human food wastes. Eggs are laid in batches of 100-200 and hatch within a day. Larvae (maggots) feed from 3-10 days then crawl away from the feeding site to pupate in soil or some drier location. Adults emerge 5-10 days later and live from two to five weeks. Because of frequenting animal excrement and human foods, blow flys pose a serious threat to human health. Diseases spread include Salmonella, dysentery, typhoid fever, cholera, hepatitis, tuberculosis, poliomyelitis and parasitic worms. Their strengths include high reproductive capacity, very short life cycle, diverse food sources and they are strong fliers. A weakness is that they tend to rest at night. This makes it possible for surface treatments to be used.