You should look for traces of the insects in the folds of your mattresses, box springs and other places where they are likely to hide. You might be able to find their papery skins, which get cast off after molting and look like popcorn kernels but are smaller and thinner, Harlan said. They also leave small, dark-colored spots from the blood-filled droppings they deposit on mattresses and furniture. If you can touch the spot with a water-soaked towel and it runs a rusty, reddish color, you're probably looking at a fresh drop of bedbug feces, Harlan said.
In comparison to other insect bites, bed bug bite marks are usually in groups of three or more when they appear on the skin. This is sometimes called the “breakfast, lunch and supper bites”. As you can see in the picture below, the bites are rather close to each other. Their bites often look like little red bumps, pimples or even blisters and welts. Some people can also mistake them for flea bites. If one of these insects bite you, you usually won’t even feel it as it uses a form of anesthetic which dulls the pain. Bed bugs also are known to leave bite marks in a straight line, also in close proximity to each other. A single bed bug can bite you a number of times during the night. However, if you have a bed bug infestation, there are usually a large number of these little pests and this can result in a multitude of bite marks. Please also remember that some people may not have a negative reaction to these bites. In fact, sometimes they are mistaken for spider bites, even by medical professionals so make sure you let your doctor know if you feel it could be a bite from bedbugs. Lastly, you will be happy to learn that bed bugs do not fly so you won’t be attacked from the air.
One bed bug will usually take more than one bite. Once a bed bug inserts its mouthparts and finds a suitable blood vessel, it will begin feeding. However, finding the right blood vessel may take more than one injection into the skin. In addition, bed bugs are very sensitive to movement by the host they are feeding on. Therefore, if a sleeping person moves, a feeding bed bug will probably withdraw its mouthparts and begin its search for a blood meal on another part of the body. It’s important to remember that the number of bites a person receives is not indicative of the number of bed bugs that feed on that person.