Bed Bug Lifecycle

Bed bugs (Cimex lectularius and Cimex hemipterus) are insects that feed exclusively on blood. They are named for their preferred habitat: human homes, specifically near or inside beds and bedding. Adult bed bugs are reddish-brown, flat, oval, and wingless.

They are usually about 4 to 5 mm long. Bed bugs have segmented abdomens with microscopic hairs that give them a banded appearance. They also have a beaklike piercing-sucking mouthpart system. The life cycle of a bed bug involves multiple stages: from egg to several nymph stages, and then the adult stage.


Female bed bugs lay between one and five eggs each day and may lie up to 500 eggs within one lifetime. Eggs are laid singly or in clusters and are placed within tight cracks or crevices. The egg is white and about 1 mm in length. Eggs typically hatch in about 10 days at room temperature.

Nymph (1st stage)

Once the egg hatches, the bed bug enters the nymphal stage. First-stage nymphs are tiny (about 1.5 mm long) and pale in color. They are somewhat transparent and can take on the color of their food (blood). They must consume a blood meal in order to molt (shed their exoskeleton and grow) into the next stage.

2nd stage

After the first blood meal, the nymph molts and enters the second stage, becoming slightly larger (about 2 mm long) and a little darker. Like all nymph stages, the 2nd stage nymph requires a blood meal to molt to the next stage.

3rd Stage

The bed bug will again require a blood meal to molt into the third stage nymph, which is larger still (around 2.5 mm long).

4th Stage

After another blood meal and molting process, the bed bug becomes a fourth stage nymph (about 3 mm long).

Adult Unfed

Once the fifth stage nymph feeds, it molts into an adult. Adult bed bugs are about 5-7 mm long, brown, and wingless. When viewed from above, their body appears oval, but when viewed from the side, bed bugs appear flat.

Adult Fed with Blood Meal

After feeding, adult bed bugs become larger, elongated, and a deep red color. They may increase in size nearly twofold after a full blood meal. The female bed bugs can lay more eggs after each feeding.

It’s worth noting that the duration of each stage can vary depending on the temperature and the availability of food (blood). The entire lifecycle from egg to adult can range from 5 weeks to 4 months.

Adult bed bugs can live up to a year under optimal conditions (with regular feeding and optimal temperature). They are capable of surviving long periods without a blood meal, making them especially resilient pests.

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