Bed bugs are visible to the naked eye, but depending on where they are in their life cycle they can be hard to see. Adult bed bugs are the easiest to spot. According to the EPA, they are roughly the size of an apple seed and the height of a credit card. Adults are flat and oval-shaped, have six legs, and are rusty red in color. Bed bug larvae, also referred to as nymphs, are white-yellow or translucent in color and are much harder to spot due to their small size. The nymphs go through five stages of life, shedding an exoskeleton at each stage. Throughout these stages the nymphs grow in size from approximately 1.5 millimeters to approximately 4.5 millimeters. Bed bug eggs can be the most challenging to see as they are roughly 1 millimeter — about the size of a pinhead — and are white or clear. Bed bugs tend to be more active at night, as this is when they feed.