Bed bugs primarily detect or find their host by the carbon dioxide trail that is emitted by humans while sleeping. The second factor that attracts bed bugs is the warmth or heat that is emitted steadily by a sleeping body. There are also certain chemicals emitted by the body while sleeping that bed bugs love. Their sensors are located in their antennas, which makes it easy for them to find the sleeping body.
Aside from these senses, it is believed that bed bugs have a compound eye structure that allows them to see in black and white. Their eyes let them pick up the heat signature emitted by the body. Since the heat signature of a sleeping body is warmer in the middle area, you will most likely find more bed bug bites on your arms, torso and legs than on the fingers and toes.
Though their eyes are not able to immediately create a full picture, they can see and sense very well that they are able to do what they are best at – finding you and feeding on you.