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Fleas (Siphonaptera)
Fleas are tiny, wingless parasites that feed on the blood of mammals and birds, with cat fleas being the most common species attacking pets and humans in the U.S. Their bites cause intense itching and allergic dermatitis, and they serve as vectors of tapeworms, murine typhus, and historically, bubonic plague. A single adult flea can produce hundreds of eggs, making infestations escalate rapidly. Effective flea control requires simultaneous treatment of pets, interior spaces, and outdoor areas to break all life cycle stages.