Some bed bug species are parasites of bats or birds, and may bite people if the wild hosts are no longer available. Although similar in overall appearance, the species of bed bugs that normally feed on bats, swallows, chimney swifts, pigeons or other wild hosts can be differentiated from those that prefer humans. Entomologists and knowledgeable pest managers can make this determination. If bat bugs or bird bugs are present, roosting and nesting sites should be the primary focus, and the animals should be removed and excluded from the building. 

The size of bed bug bites varies with a number of different factors. Bed bugs inject an anti-coagulant along with their saliva when they pierce the skin to take a blood meal. This anti-coagulant is mostly responsible for how a person reacts to the bite and determines the size of the bug’s bite. Since people will have various sensitivities to the bed bug’s bite, the size of the bite will vary, as well. Another factor that influences the size of a bed bug reaction is the number of times a person is bitten. Bite reactions of people bitten many times are also variable, and their response may be either more or less intense as the number of bites increases.
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