32 PARASITOLOGY. 
The legs are thick and strong, terminating in two 
hooklets or claws. The posterior pair are the long- 
est, giving them great power to jump. 
Life Cycle.—The eggs are ovoid in shape and 
brown in color; they hatch in from six to twelve 
days, depending upon the temperature. The larvae 
are worm-like and are composed of thirteen seg- 
ments. The mouth parts are arranged for mastica- 
tion. The larval stage lasts about eleven days; they 
then pass their pupal stage in tough brown cocoons. 
The cocoon stage lasts about fourteen days. 
Fleas breed in filth, carpets, rugs, kennels and 
barns. 
Animal Infested.—Man. 
Injury to Host.—In the adult state they attack the 
skin. The puncture causes itching and inflammation. 
Treatment.—Cleanliness; pyrethrum or tobacco 
dust sprinkled in the infested quarters. 
PuLEX SERRATICEPS (Seco—to cut). 
Synonym.—Ctenocephalus Canis, dog and cat flea 
(Fleon—to flee). 
History —Universally found. 
Description.—Similar in appearance to the Pulex 
Irritans, with the exception that it is provided with 
fifteen to eighteen spines on the posterior margin of 
the pro-thorax. In the preceding species the thorax 
is entirely nude. 
Life Cycle.—EHighteen to twenty eggs are laid in 
some dirty or dusty corner, which pass through the 
same stages as the preceding species. 
Animals Infested.—They attack the cuticular sur- 
face of dogs, cats and men. 
Treatment.—Dogs can be dipped in a five per-cent 
