Their significance lies in their blood feeding abilities as adults, their broad host range, and their ability to transmit several important disease agents.
Some fleas can also serve as intermediate hosts for helminth infections.
Mouth parts of adults adapted for feeding on blood, mouth parts of larvae adapted for chewing. The general life cycle involves eggs being laid while adults are on the host but they do not become attached. Instead, the eggs fall off to the floor or bedding. Larvae feed on feces, blood, etc. The larval period lasts 1 to 2 weeks but may be extended to several months.