2 BULLETIN 45, U. S. DEPARTMENT OF AGRICULTURE. 



In the evening of June 3 the sheep were driven onto the school 

 section into a small corral previously prepared for them. On the 

 morning- of June 4, and thereafter until the evening of June 14, the 

 sheep were herded twice a clay for about two hours at each feeding. 

 For the remainder of the time they were kept in the corral. About 

 three-fourths of the time the sheep were herded, they were allowed 

 to run at will, and the other one-fourth they were driven and made 

 to feed in places known to be well infested with ticks. During all 

 this time the development of the ticks was Watched on some of the 

 sheep, and when it was found that some of the ticks were nearly 

 engorged the sheep were driven to the camp laboratory, about a mile 

 from the sheep corral. At the camp the sheep were examined, usu- 

 ally twice a day, so that the development of the attached ticks might 

 be followed, and any females that were engorged, or nearly so, were 

 removed. Here the sheep were allowed their freedom the greater 

 part of the day, but at night were confined in a shed. It is probable 

 that they picked up a tick or two about camp, but probably only a 

 very few. 



Two thorough examinations were made of each sheep, to locate the 

 living ticks and to remove the dead ones. The first examination be- 

 gan on June 10 and was finished on June 15 ; the second was started 

 on June 23 and ended on June 27. Besides these examinations 

 numerous less thorough examinations were made, any dead ticks 

 found being removed and the living ones noted. 



Near the completion of this experiment two sheep were selected 

 from the adult sheep with heavy wool, and after thorough examina- 

 tions were utilized in another experiment. Ticks were collected by 

 dragging cloths over the ground and placed on these sheep. They 

 were first put on one sheep June 20 and on the other June 25. Until 

 June 28 these sheep were allowed to run with the others, but after 

 that time the other sheep were driven back to the owner and the 

 two were taken out to feed. They were examined twice a day. 



OBSERVATIONS AND RESULTS. 



In order to show as exactly as possible the results obtained, the 20 

 sheep have been divided into three groups, namely, unsheared lambs, 

 unsheared sheep, and sheared sheep. In the first group were 8 

 spring lambs, Xos. 2-0, inclusive; in the second group were 7 adult 

 sheep with heavy wool, Xos. 10-10, inclusive, and in the third group 

 were the ram and 4 sheared adult sheep, Nos. 1 and 17-20, inclusive. 



The results have been summarized in Table I. The heading, " total 

 dead unfed ticks " includes all males and females which were thought 

 to have been killed before having fed to anjr extent. It may also 

 include, besides males which had not fed to any extent, males which 

 had fed considerably, for it is usually impossible to distinguish fed 



