An adult bedbug is between 3/16 inch and 1/4 inch long. The U.S. Environmental Protection Agency indicates that an adult bedbug is about the same sizes as an apple seed.
If it has not fed recently, the adult bedbug is mahogany or rusty brown, and its body is flat and has an oval shape. If the bedbug has fed recently, its body is red or reddish-brown and has more of a balloon-like shape.
Juvenile bedbugs, known as nymphs, are 0.05 inch to 0.2 inch long. They tend to be colorless or translucent, which makes them harder to spot than adult bedbugs.
Bedbug eggs are about 0.04 inch long, roughly the size of the head of a pin. The eggs are white and hard to see with the naked eye.