Baby bed bugs are much smaller than adults and require a greater amount of food to develop. Once they hatch, they will molt and feed several times a day, and their bodies will darken. Once they reach maturity, they will reproduce, adding more bugs to your infestation. The size of the baby bed bug is approximately the same as the size of a quarter.
Although they are flat in shape, they still have tiny stumps on their abdomens where their wings used to be attached. Whether the bugs are baby or adult, they remain flat when resting but they expand their abdomens when they feed. Observing a bed bug under a microscope is a good way to determine their size. However, the same thing cannot be done in a real world situation.
Baby bed bugs are very difficult to see with the naked eye. The first stage of the life cycle is nymphs, which are one-tenth the size of an adult bed bug. The second stage is a third of the size of the adult bed bug. The third stage is about half the size of an adult, and the fourth stage is the largest stage. As the bugs grow older, they develop a brown coloration on their bodies.
As the adults, bed bugs can reach a size of five to six millimeters. The size of adult bed bugs is similar to that of a cockroach, but they can be harder to spot. They grow faster than cockroaches and will run away if they see the light.