Fleas are wingless insects that are agile, usually dark colored with tube-like mouth-parts adapted to feeding on the blood of their hosts. Their legs are long, the hind pair well adapted for jumping. The flea body is hard and is able to withstand great pressure, polished, and covered with many hairs and short spines directed backward which also assist its movements on the host. Its total life span can be as short as one year, but may be several years in ideal conditions. Female fleas can lay 5000 or more eggs over their life, allowing for phenomenal growth rates. Average 30–90 days. Fleas are vertically flat like a fish, and can move easily through the hair of a host. Common hiding places for cat fleas include seams in mattresses and box springs, cracks in bed frames, under loose wallpaper, behind picture frames, and inside furniture and upholstery. They will bite people-especially when they cannot find their usual animal host or if they become very numerous. Their bites often leave a small, red, irritated area on human skin.