The bed bug life cycle has three stages: egg, nymph and adult. Eggs hatch in about a week, nymphs molt five times and need a blood meal before each molt, and at room temperature a bed bug can go from egg to adult in about a month. Adults live around 10 months on average, and a female lays one to several eggs a day, adding up to hundreds in her lifetime.
Table of Contents
Bed Bug Life Cycle at a Glance
| Stage | Size | Color | How long it lasts* |
|---|---|---|---|
| Egg | 1 mm (a pinhead) | Pearl white | About 6 to 10 days |
| 1st instar nymph | 1.5 mm | Clear to whitish-yellow | About 1 week, after one blood meal |
| 2nd instar nymph | 2 mm | Whitish-yellow | About 1 week |
| 3rd instar nymph | 2.5 mm | Yellow-tan | About 1 week |
| 4th instar nymph | 3 mm | Tan | About 1 week |
| 5th instar nymph | 4.5 mm | Light brown | About 1 week |
| Adult | 5 to 7 mm (an apple seed) | Brown; reddish after feeding | About 10 months on average |
*At 70 to 80°F with regular access to blood. Each stage takes longer in cooler rooms or without a host.
Stage 1: Bed Bug Eggs
Bed bug eggs are about 1 millimeter long, pearl white and shaped like a tiny grain of rice. A sticky coating glues them into cracks and seams: mattress piping, bed frame joints, the backs of headboards and furniture crevices. Eggs older than five days show a dark eye spot. At room temperature they hatch in about a week, leaving empty, flattened shells behind.
Eggs are the hardest stage to kill with sprays, which is why most treatments need a follow-up two weeks later. Sustained heat kills eggs: about 118°F held for 90 minutes, or 122°F for a shorter time. See bed bug eggs for close-up pictures.
Stage 2: Nymphs (Baby Bed Bugs)
Baby bed bugs, called nymphs, look like small, pale adults. A newly hatched nymph is about 1.5 millimeters long, the size of a poppy seed, and nearly clear, which makes it hard to see until it feeds. After a blood meal its body turns bright red and swells, and the blood shows through the skin.
Nymphs pass through five stages, called instars. Each one needs at least one full blood meal before it can molt to the next, and each molt leaves behind an empty shell. Those shed skins build up in hiding places and are one of the clearest signs of an infestation. See bed bug shells.
Stage 3: Adult Bed Bugs
Adults are 5 to 7 millimeters long (3/16 to 1/4 inch), about the size of an apple seed. Unfed, they are flat, oval and brown. After feeding they swell, turn reddish-brown and become longer. Adults feed every few days to a week when a host is available, and females need a blood meal to produce eggs.
A female lays one, two or more eggs a day and hundreds over her life. With multiple generations a year, a small introduction can grow into a heavy infestation within a few months. Compare with look-alikes in what bed bugs look like.
How Long Is the Bed Bug Life Cycle?
Under good conditions, 70 to 80°F with a person to feed on, the full cycle from egg to egg-laying adult takes about a month. In cooler homes or without regular meals it can take several months.
How long bed bugs live without feeding
Nymphs and adults can survive months without a meal. In a typical heated or air-conditioned home, that is about 1 to 4 months. In cool conditions, 55°F or below, they can last a year or more. This is why leaving a home empty for a few weeks rarely gets rid of bed bugs. Read more in how long bed bugs live without food.
What the Life Cycle Means for Treatment
- Plan for at least two treatments, about two weeks apart, to kill nymphs that hatch from eggs that survived the first round.
- Keep monitoring for 6 to 8 weeks after the last treatment. Interceptor cups under bed legs show whether any bugs are still active.
- Heat treatment kills every stage, eggs included, in one visit when done correctly. See bed bug heat treatment.
- Encase the mattress and box spring so any bugs or eggs inside are trapped until they die.
Check whether treatment worked with how to know bed bugs are gone.
Tools that match the life cycle
- Interceptor cups to catch bugs and monitor after treatment
- Mattress and box spring encasements to trap eggs and bugs inside until they die
- Steamer to kill eggs in seams and crevices
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Bed Bug Life Cycle FAQs
At room temperature bed bug eggs hatch in about a week, usually 6 to 10 days. Cooler temperatures slow hatching.
At 70 to 80°F with regular blood meals, a bed bug goes from egg to adult in about a month. It passes through five nymph stages and needs a blood meal before each molt.
Baby bed bugs (nymphs) are 1.5 to 4.5 mm long, pale and almost clear, and shaped like small adults. They turn bright red and swell after feeding.
A female bed bug lays one to several eggs a day and hundreds over her lifetime, which is why infestations grow quickly.
Adult bed bugs live about 10 months on average. They can survive 1 to 4 months without feeding in a typical home, and a year or longer in cool conditions.
Sources
- US EPA: Bed bugs appearance and life cycle
- University of Kentucky Entomology: Bed bugs
- CDC: About bed bugs
Facts in this guide are checked against the sources above and reviewed when they change. See how we research in our editorial policy.
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