The first step in detecting bed bugs is being able to identify them. Bed bugs flat and board shaped and have antennae, 6 legs, and adults are ¼ inch long. Nymphs range in size from 1.3 to 5mm. Unfed adults are a mahogany color and engorged adults are a reddish brown. The nymph are colorless. Learn more about what bed bugs look like.Once you know what the insects themselves look like it is important to know other signs of infestation. Bed bugs are wonderful hiders and are also nocturnal. You may not see the bugs themselves but if you have a bed bug problem, you should be able to spot these other signs of bed bugs anytime of the day.