74 Annals Entomological Society of America [Vol. III. 



l)lu,L( the mouth of the tuhe as the fleas did not attempt to jump 

 out when ^ivcn an opportunity to do so. Even' when placed 

 within a half inch of the ojjcn end of the tube with the head of 

 the insect turned towards the light, the fleas reversed and 

 jumped towards the closed end of the tube. This was repeated 

 by tilting the mouth downward to offer an easier exit through the 

 open mouth ; but even this inducement did not influence the fleas, 

 which invariably sought the closed end of the tube in the shadow. 

 This was tried with squirrel and rat fleas as well as with human 

 fleas and always with the same result. 



LONGEVITY OF THE CALIFORXIA FLEA. 



The great life of our native parasites seems to be anticipated 

 at the very incubation. Eggs are laid at all times. We have 

 observed oviposition during ex'cry month. The broods appear 

 to be constant and the number irregular. The incubation stage 

 of our Eastern forms taken from the obser\-ations of Pergande 

 consumes 2-4 days ordinarily. Two days is given as the incuba- 

 tion period for the cheopis in India. Our experience with this 

 species is a duration varying from 9 to 13 days at room tempera- 

 ture. When eggs of this species were subjected to identical con- 

 ditions in which wild rats were caged in the laboratory basement 

 (at a temperature of 20° to 25° C.) the length of the egg stage was 

 19 days. 



Larval life is cited by Eastern and English authorities as a 

 minimum of 8 days and a maximum of 24 days. The larval stage 

 of our California fleas under laboratory conditions is never less 

 than 28 days, often 30 days and sometimes longer. 



Pergande found that the pupal or cocoon stage of the Pulex 

 irritans varied from five to seven days in the summer months at 

 Washington. Other authors working with this species give 

 twelve days during summer months. We have observed several 

 instances of cocoon life during the warm days of September. 

 Thirty days appear to be spent in this stage. 



The entire life cycle including adult life is given by several 

 authors as four to six weeks. The British Indian Plague Com- 

 mission gives as the time necessary for the completion of the 

 cycle of development (in the case of L. cheopis) that is from the 

 egg to the imago, as 21 to 22 days. 



The following is given as a type of the life cycle observed in 

 C. aciitiis. This specimen was kept under observation from the 



