Flea Hazards Severe flea infestations can cause intense itching, skin lesions, anemia, weight loss and restlessness. Fleas transmit tapeworms and are know carriers of diseases like tularemia, murine typhus, and the plague. Flea Lifecycle Eggs are laid on the host and fall off. Pupae hatch within a few days, and immediately seek a host. Larvae hatch within a few weeks and feed on organic debris, than spin a cocoon.
Adults immediately seek a warm-blooded host such as dogs, cats etc.