Bed bugs are small insects that feed exclusively on blood. The common bed bug, Cimex lectularius, prefers to feed on the blood of humans but will feed on nearby pets in some situations.
Bed bugs do not live on humans or animals. In general, they prefer to stay hidden unless they are actively seeking or taking a blood meal. Bed bugs tend to be nocturnal insects, meaning they are active and looking for a blood meal at night. In some situations, bed bugs can become active during the daytime hours.
An interesting characteristic about bed bugs is that they are very flat insects unless they have recently taken a blood meal. Their flat body shape allows them to fit into very small cracks and tight crevices. If a credit card can fit into a crevice, there is plenty of room for a full grown adult bed bug to hide!
Bed bugs grow through five immature life stages, or instars, before they reach the adult stage. Before a bed bug can grow from one instar to the next, they must take a blood meal.
Most bed bugs will seek out a blood meal every few days. If a blood meal is not available, bed bugs can go for weeks to months without feeding.
All stages of the bed bug, including the eggs, can be seen with the naked eye. The eggs and first instar stage bed bugs can be difficult to identify. They are very small, about the size of a poppy seed, and may be clear or white in color. Adult bed bugs are larger, about the size of an apple seed, and are dark red or brown in color.