420 ENTOMOLOGICAL SOCIETY 



In the Hemiptera the strictly parasitic forms are contained in a 

 distinct group, which presents well-marked characters, and suffi 

 ciently departs from the normal structure to indicate a considera 

 ble antiquity. Yet, while the relationships are somewhat obscured, 

 there is no reason to look for their origin elsewhere than among 

 the free forms of the order or in some generalized, non-parasitic 

 type. The common bedbug well illustrates the general effect of the 

 assumption of parasitic habit, and no great amount of modification 

 were required to transform it into some of the least specialized 

 Pediculids. Acanthia is not the only genus of Heteroptera which 

 has a taste for mammalian blood, and the sedentary habits of the 

 lice are easily derived from a former freer existence, and would, 

 indeed, inevitably follow, as the general law in parasitism, when 

 ever sufficient security from interference should accompany it. 



The fact that the Pediculidae have assumed such distinctive 

 structure and have the parasitic habit so firmly established may 

 be taken as evidence that they assumed the parasitic habit at a 

 comparatively early date in the development of the mammalian 

 animals, and have adapted themselves to their various hosts through 

 a prolonged period. 



In the Mallophaga we have a group so well defined and sepa 

 rated from other insects that their true affinities have educed 

 much discussion. Their relations to the Termites and Psocidas 

 among the Pseudo-Neuroptera are now generally recognized, 

 however. Many of the Psocidae normally inhabit such places as 

 would most readily bring them in contact with birds or mam 

 mals, and they have, indeed, been mistaken for parasitic lice and 

 thought to be infesting fowls in chicken-houses or horses and 

 cattle in their stalls. The Mallophaga feed upon the epidermal 

 scales, hairs, feathers, or tegumentary excretion of the animals 

 they attack, and, except in cases of exudations of blood upon the 

 surface, are not supposed to indulge in blood. The PsocidaB feed 

 rather on dead vegetal matter, though Atropos and Clothilla are 

 not strictly herbivorous, as is evidenced by their attacks upon 

 book-bindings, etc. (which involve the sizing and the leathery 

 portion) , and upon preserved insects. They even attack children, 

 causing at times considerable annoyance by their bites. 



We must remember, also, that many of the Mallophaga even 

 now leave their hosts and secrete themselves, during portions of 



