Bed bugs have five instars, or developmental stages, and change from egg-like stages to adults within a matter of weeks. The first stage of bed bugs is known as the nymph, which is about 1.5 millimeters long. Once it hatches, the bug begins feeding and will eventually molt into its second stage. The second stage of bedbugs is about 2.5 millimeters long, and the third stage is about three millimeters long. At this stage, bedbugs have an average lifespan of four to six months. However, this may extend to a year in cool environments.
Bedbugs feed once every two to three days. In colder weather, they feed less frequently. The size of an adult bedbug is between 1 and 3 mm. Female bedbugs are approximately the same size as an adult. They feed on blood during the first few days of their life. A female bedbug is approximately one-half an inch long when fully grown. During the day, the bugs hide away. They feed for between two and five minutes before molting. Bedbugs can have three or more generations a year.
Bedbugs are oval and wingless insects with six legs. They are about one-quarter of an inch in length, and have a flat body with well-developed antennae. Their eyes are small and compound. They also have a pronotum, which is a bump behind the head.