4 FARMERS' BULLETIN 909. 



more loss than is commonly supposed. The lowering of the vitality 

 and the general unthrifty condition produced by lice often result 

 in an increased percentage of death loss among cattle during unfa- 

 vorable seasons. 



Calves, young stock, and old, weak, poorly nourished cattle suffer 

 most from the ravages of lice. Heavily infested calves do not grow 

 and thrive or gain weight normally during the winter season, and 

 often remain stunted until the old coat of hair is shed in the spring, 

 when most of the lice disappear. The animals then may grow and 

 fatten, but the loss experienced during the period of arrested growth 

 is a loss not easily regained. Lice act as a contributing cause to 

 increase the death rate among poorly nourished cattle of low vitality, 

 especially old range cows exposed to inclement weather. Although 



mature cattle in 

 lull vigor suffer 

 less seriously from 

 infestation with 

 lice, nevertheless if 

 they become very 

 lousy they will 

 not gain weight 

 and there will be 

 a loss in the pro- 

 duction of either 

 meat or milk. 

 The damages and 

 losses caused by 

 lice are of suffi- 

 cient importance 

 to warrant careful 

 consideration and 

 the application of 

 proper treatment. 

 Three kinds or species of lice are commonly found on cattle in the 

 United States. Two of these are blood suckers, or suctorial lice, and 

 are commonly known as "blue lice." The third species is a biting 

 louse commonly known as the " little red louse." 



SUCTORIAL LICE. 



The short-nosed cattle louse (H cematopinus eurysternus, fig. I) 1 

 usually is found on mature cattle, although it may occur on calves 

 and young stock. The average length of adult females is about 

 one-eighth of an inch and the body is about one-half as broad as 



FIG. 1. Short-nosed cattle louse (Hannatopinii* evrystemvs) 

 Female. (Magnified about 20 times.) 



1 Figures 1 to 3 are from photomicrographs by Dr. W. T. Huffman. 



