There is no easy way to say it... bed bugs want to suck your blood! No, really, that is what they feed on: your blood, Particularly when you are snuggled in your bed and your temperature rises, signaling to bed bugs dinner is served. Bed bugs are small, flat wingless insects that are reddish-brown in color and approximately one-quarter inch long, before feeding, about the size of a small apple seed. They come out at night and are fast crawlers.