870 SIPHONAPTERA AND COLEOPTERA 



Life-History.— The eggs are round, waxy-white or pearly m 

 colour, and number one to five at each oviposition. They hatch 

 in Bombay in two days, and produce the little larvae, which at once 

 hide themselves away from the light. In about a week's time these 

 larvae, which at first are very active, become sluggish, and, ceasmg 

 to eat, spin cocoons composed of fine white silk-like fibres. The 

 cocoon becomes covered with rubbish, and is hard to see. In about 

 seven to fourteen days the imago escapes from the cocoon. The 

 total development, therefore, requires about twenty-one to twenty- 

 two days. 



Bionomics.— The young flea is capable of living without a feed 

 of blood for some seven to fourteen days, but if not fed then it dies. 

 The length of life of a flea is difficult to ascertain, but Xenopsylla 

 cheopis will live forty-one days on a rat and twenty-seven days on a 

 man. Therefore, the whole life of a rat-flea from birth to death is 

 about sixty-three days. A rat -flea is more readily attracted by a 

 . rat than by a man. It breeds at all temperatures, but has one 

 optimum temperature above and below which it does not thrive 

 so well. Dampness is injurious to the flea, killing the larvae and 

 hindering development. 



X. cheopis is the commonest rat -flea, being probably the flea oi 

 Epimys norvegictis in India, while in Western Europe Ceratophylh:s 

 fasciatus is the flea of the same rodent. It is found on E. norvegtcus, 

 E. rattus, and Nesokia bengaliensis ; also on musk-rats, guinea- 

 pigs, cats, rabbits, antelopes, kangaroos, and men. 



The infection with plague bacilli does not appear to affect the 

 flea's health, for it has an immunity dependent, apparently, on 

 phagocytosis. 



Hoplopsyllus Baker. 

 Closely related to Pulex, but distinguished at once by the ctenidia 

 on the prothorax. Hoplopsyllus anomalus Baker is the plague carrier 

 of the Californian ground squirrel. 



Family Ceratopsyllid^ Baker, 1905. 



Siphonaptera with ctenidia present on the metathorax and abdomen; eyes 

 rudimentary or absent. 



Genus. — Ceratopsyllus Kolenati. 



The species of this genus are found on bats. 



-Jit. \ JSS^ 



Fig. 460. — Larva of a Beetle passed per Urethral. 

 (After King.) 



