Tapeworm eggs are dropped from tapeworms that crawl out of the anus of infested dogs or cats. One study reported that 24 percent of dogs and 30 percent of cats carried the tapeworm. Another study reported that approximately 1.1 percent of the fleas are infected with tapeworm. In order for proper egg development, female fleas must ingest a blood meal from a host such as a cat or dog. Usually a flea cannot complete its life-cycle on human blood.
Females lay eggs on the host.
The eggs have smooth shells and are not stuck to the host, so they roll off into the host's surroundings. Adult fleas that have taken a blood meal will excrete partially digested blood in their feces. Smooth-shelled eggs that roll off of host along with partially digested blood that will become larval food source. The egg stage is easily vacuumed up and discarded. Flea larva that will feed on the partially digested blood excreted by adults.