Fleas are small insects (under 1/4 inch) and are dark brown in color. They lack wings and are extremely narrow side to side, which enables them to move easily through the body hairs. Their last pair of legs is modified for jumping. They have numerous spines and hairs on their body, and their mouthparts are adapted for piercing the skin and sucking blood. The whisker-like spines on and near the head are important characteristics used in the identification of fleas.

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