306 ENTOMOLOGICAL NEWS [xxxii, '21 ' 



dry blood instead of other foods was fed to larvae the life 

 cycle was considerably shortened. 



While collecting eggs from the mats of dogs and cats on 

 several occasions, adult flea feces were observed in rather large 

 amounts, and as these are the source of food for most of the 

 larvae in nature, enough material was gathered to conduct an 

 experiment. The larvae, in cages, fed entirely upon this, pro- 

 duced adults in 15 and 16 days respectively. No such results 

 were obtained when they were fed upon other food. The 

 blood used in other experiments was from a human source, 

 and the larvae seem to obtain certain ingredients from the flea 

 feces that were not present in the human blood, for the life 

 cycle in the former case was considerably shorter. 



LIFE HISTORY 22 DAYS. 



A very close record was kept of 5,997 eggs from the time 

 they were laid until adults emerged, and the following shows 

 the results : 



Number of eggs : 5997. Average number of days to hatch : 4. Per 

 cent hatched : 75. Average number of days from egg hatching to pupa : 

 14. Average number of days for pupa: 4. 



If adults were fed daily they could be kept alive for a period 

 of thirty to forty days. 



FLEAS ON RATS. 



Twenty-five rats were captured alive in several open lots in 

 Boston and not a single rat flea was secured. In Wayland, 

 Massachusetts, twelve rats were caught and from these 57 

 adult rat fleas were removed. In Brighton, Massachusetts, a 

 total of over 100 rats was captured and from these six rat 

 fleas were removed. The large number of rats in Brighton 

 and the scarcity of fleas led to further investigations. The 

 boards were removed from one of the stable floors and under 

 here many rat nests were found, and in every nest eggs, larvae 

 and adult fleas were present in large numbers. As high as 

 C0 adults were removed from one nest and there was not 

 one nest that did not give a small number of adults, many 

 of which contained fresh mammalian blood. Why the fleas 

 did not remain upon the rats can be partially explained by the 



