Its size depends on how recently it has eaten a blood meal. The upper surface of its body has a papery, crinkly, flimsy appearance. When engorged with blood, its body becomes elongated and swollen, and its color changes from brown to dull red. The color, size, and shape change from an unfed to a full bug is remarkable. Under favorable conditions the female bed bug lays about 200 eggs at the rate of 3 or 4 per day.
Eggs have a sticky coating and stick to objects where they are laid.
It usually takes the eggs 6 to 17 days to hatch, and the newly emerged nymphs will feed immediately. Depending on environmental factors and the availability of food, there can be considerable variation in developmental rate. Bed bugs may live for several weeks to several months without feeding, depending on temperature. A bed bug generally feeds at night, but if it is hungry and the area has a dim light, it may feed during the day. A bed bug generally pierces the skin of humans as they sleep.