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 realinjury. 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 (J/enopon 
pallidum), 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 scmetimes 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 Mallophaga is divided into the two sub-orders 
TIschnocera and Amblycera; 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- 
lowing genera: TZrichodectes, Docophorus, Goniodes, Gonio- 
cotes and Ornithobius belong to the /schnocera, and Calpocepha- 
lum, Trinotum and Menopon to the Amblicera. To avoid 
unnecessary repetition of technical details these parasites 
have been arranged according to the hosts they infest, and 
not according to a scientific classification. 
We will first describe the hair-lice found only upon our 
domesticated animals. All belong to the genus 7richodecies; 
