Bed bugs develop from eggs into larvae and then adults in about one month, but they may also spend several months as larvae. The larvae require blood meals in order to shed their exoskeletons, a process called molting, and enter the next of the five stages of larval development.
Bed bugs turn from larvae directly into adults, without passing through a pupal stage as many insects do. They undergo simple metamorphosis, in contrast to complete metamorphosis, which includes a pupal stage. Larvae of insects that do not go through complete metamorphosis are also called nymphs. Bed bug nymphs become larger and change shape slightly each time they molt.