PULICID^E. 



389 



pressed. There are four long hairs on the side of each ring, 

 becoming longer towards the end of the abdomen, where they 

 are longer than the body is thick. The terminal segment of 

 the body is considerably smaller than the one preceding it, and 

 has two long spines arising from the tergal part of the ring ; 

 these spines seem to assist the larva in moving through the 

 hairs and dust in which it lives. The well developed head is 

 rounded, conical, narrower than the prothoracic ring, pale 

 honey yellow, and with long three-jointed antennae. 



Mr. Emerton, who made the drawings here given, informs 

 me that the larvae, when fifteen days old, did not differ from 

 those freshly hatched. I have been unable to discover that it 

 moults. Westwood states that "when fully grown, which 

 occurs in summer in about twelve days, the larvae enclose 

 themselves in a 

 small cocoon of 

 silk. Rosel, how- 

 ever, observed 

 that some of the 

 larvae underwent 

 their transforma- 

 tions without 

 forming any co- 

 coon." "The pu- 

 pa is quite inac- 

 tive, with the legs 

 enclosed in separate cases. The period of the duration of 

 the pupa state varies from eleven to sixteen days." Our 

 specimens were hatched early in October, and they probably 

 pass the winter before changing, as Westwood states that 

 they pass the winter in the larva state. The species here rep- 

 resented (Fig. 310, &, maxillae, and their palpi, a d, the man- 

 dibles, which are minutely serrated ; c, labial palpi, the labium 

 not being shown in the figure) was found on the person of a 

 man, though it seems to differ specifically from Westwood's 

 figure of P. irritans Linn., the human flea ; other species live 

 on the dog, cat, squirrel, and other quadrupeds and various 

 birds. The antennae are concealed in a small cavity situated 

 behind the simple eyes and are four-jointed ; in P. musculi 



Fig. 310. 



