118 MISC. PUBLICATION 5 0, 17. S. DEPT. OF AGRICULTURE 



hosts, at least two of which are known, the pig and the prairie dog. 

 In the city of Washington it is questionable whether there is a true 

 infestation, and C. Fox and Sullivan (&£, p. 1917) found that of the 

 4,408 fleas taken in the rat-flea survey of New York City, extending 

 from April 18, 1923, to February 28, 1925, not a single specimen was 

 Pulex irritans. 



Concerning the occurrence of this flea in the United States, Trembley 

 and Bishop (76) state: 



* * * The human flea causes severe annoyance in buildings, farmhouses, 

 stables, and surrounding premises, especially in the Middle West and South and 

 on the Pacific Coast. It is the predominant species affecting man on the Pacific- 

 Coast. 



Bacot (1) has done much work on the biology and ecology of irritans. 

 He found that cold (40.9° F.) was fatal to the eggs and that warmth 

 (75° F.) combined with low humidity favored the fertility of the 

 eggs. According to Bacot the newly hatched larvae were abie to sur- 

 vive for several days to over a month without food. The cocoon period 

 ranged from 7 to 239 days, and adults, at 45°-50° F. with nearly 

 saturated air, lived without food for 125 days. 



Pulex irritans varies considerably in America. Besides the variety 

 dugesii Baker, already considered in this paper, Cunha (£, p. 134) 

 described in 1914, as a new American variety, bahiensis, from Brazil. 



Trie Genus Juxtapulex Wagner 



(Fig. 12, B) 



Juxtapulex Wagner. 1933. Berlin Zool. Mus. Mitt. 18: 341. Type, Juxtapulex 

 echidnophagoides Wagner (by original designation). 



Front with anterior margin either broadly rounded or angulate. Eyes sub- 

 angulate ventrally. Two setae in ocular row. Antennal groove closed. Gena 

 with broad ventral lobe; genal comb composed of 2 short, apically angulate, 

 brown, spinelike processes on posteroventral aspect of gena. Mandibles enlarged, 

 extending almost to apex of coxa I. Labial palpus indistinctly 4-segmented. 

 Metepimeron very much more extended vertically than longitudinally. Hind coxa 

 with a row or patch of spinelets on inner surface. Sternal plate VIII of male 

 large, broad, unmodified. 



Juxtapulex Wagner was established for two North American species, 

 the type species and Pulex porcinus Jordan and Rothschild. As 

 pointed out by Wagner, the genus, through the characters of its type 

 species, shows a decided affinity with Echidnophaga OllifT. 



Juxtapulex echidnophagoides Wagner 



Juxtapulex echidnophagoides Wagner, 1933, Berlin Zool. Mus. Mitt. 18 : 343, 

 fig. 1A and figs. 2-6. 



Type host. — "Dasypus novemcinctus" (nine-banded armadillo). 



Type locality. — East of Cartago, Costa Kica. 



Range. — Known only from Costa Rica. 



The original description of this species is extensive and accom- 

 panied with six detail drawings. Juxtapulex echidnophagoides is 

 easily distinguished from /. porcinus (Jordan and Rothschild) be- 

 cause of the angulate front margin of its head. This margin in 

 porcinus is broadly rounded as in most fleas. 



