FEATHER OR HAIR-LICE. 109 



The food of these parasites, which possess a biting and 

 not, like true lice, a sucking mouth, consists of epidermal 

 cells and minute particles of hairs and feathers. If they are 

 very numerous they cause their host a great deal of incon- 

 venience and real injury. This is almost entirely caused by 

 their sharp claws, which irritate the host, thus making rest 

 impossible, and not so much by any abstraction of food, as 

 has frequently been claimed. The ear-shaped crop of these 

 parasites, filled with food, and located in the abdomen, has 

 been dissected again and again, but no blood could be found. 



These insects remain for life upon the body of their hosts, 

 though some, like the common louse of the hen {Menopon 

 jjalViduni), are sometimes found walking upon the roosts. 

 Yet they are by no means stationary, but move about so 

 rapidly among the feathers and hairs that they are not 

 readily captured. In this manner they can reach, by actual 

 emigration, other birds of their kind, since these usually asso- 

 ciate together. Birds, infested by such lice, though they 

 "would furnish the same amount of food after death as before, 

 •are still no longer suitable abodes for these parasites, for 

 they require not only food but warm shelters. This is the 

 reason why dead game-birds and poultry are sometimes such 

 unpleasant objects to handle, as the lice are leaving them 

 for warm places, very much to the disgust of cooks and tax- 

 idermists. 



The order Ifallophaga is divided into the two sub-orders 

 IscKnocera and Amhlycera\ insects belonging to the former 

 have three to five-jointed, filiform feelers and no labial palpi; 

 those belonging to the latter have club-shaped, four-jointed 

 feelers and four-jointed labial palpi. Of the feather-lice found 

 upon domesticated animals and birds in Minnesota the fol- 

 lo"wing genera: Trlchodectes^ Docophorus^ Goniodes^ Gonio- 

 •cotes and Ornithohius belong to tht Ischnocera^ and Caljjoceplia- 

 lum^ Trinotwm and Menopon to the Amhlicera. To avoid 

 unnecessary repetition of technical details these parasites 

 have been arranged according to the hosts they infest, and 

 mot according to a scientific classification. 



We w^ill first describe the hair-lice found only upon our 

 domesticated animals. All belong to the genus Trlchodectes; 



