SOME PESTS OF OHIO SHEEP 



61 



The lambs were weighed individually each week so that a com- 

 parison of gains made could be readily ascertained. It was easy 

 also to determine the relative number of ticks and lice infesting 

 each sheep. It was found that the lambs heavily infested were the 

 ones that did not gain. Table I shows changes in weight during 1 

 week as well as the degree of infestation at the time. It will be 

 noted that sheep numbers 190 and 226, having but few lice and no 

 ticks, made gains during the week while the others either remained 

 nearly the same or lost in weight. Of course it would be difficult to 

 determine from these data the exact role played by ticks and lice 

 separately in reducing the weight. Both parasites finally became 

 so abundant as to interfere with the object of the experiment. 



TABLE I.— COMPARISON OF LOSS OR GAIN IN WEIGHT AND DEGREE 

 OF INFESTATION WITH LICE AND TICKS 



Lot 1 



"Heavy infestation" as used in the table, means that one had 

 no difficulty in finding ticks or lice on any part of the animal. From 

 the foregoing it is evident that the sheep tick causes a shrinkage in 

 weight, and unthrifty condition of the infested animal and a rag- 

 ged, taggy coat of wool. The vitality of the animal is also much 

 reduced so that it cannot offer normal resistance to the attacks of 

 other parasites or diseases. 



The tick. — The sheep tick is, according to entomologists, a 

 wingless fly, hence it is in no way directly related to the true ticks. 

 A true tick has in the adult stage eight legs, while the so-called 

 sheep tick has only six legs and in general form and structure is 

 quite different. 



The life cycle of the tick is unlike that of most of its kin, the 

 flies. The egg and larva develop within the female which finally 

 deposits her offspring in the pupal stage. The pupa is a hard 

 shelled, seed-like body, at first a pale color, later turning brown. 

 On the inside of the shell changes are in progress which in time re- 

 sult in a young tick, which breaks open the shell at one end and 



