6 BULLETIN 141, U. S. DEPARTMENT OF AGRICULTURE. 



The seed ticks were applied by permitting them to crawl on to 

 the cow's hair in various places from the edge of pint fruit jars 

 used in hatching them. Sufficient time was allowed after hatching 

 to permit the seed ticks to harden and become brown. They had 

 been confined in the jars by cotton cloth. Tins cloth was used 

 later to wipe up the ticks and scatter them over the cattle. In the 

 first period of the experiment the ticks were mainly placed on the 

 backs, bellies, and escutcheons of the cows, but in the second period 

 they were placed more generally over the entire body. 



Some of the tick masses became too moist during oviposition and 

 incubation in the wet season, and this caused the masses to adhere 

 and resulted in the death of the larva?, especially when too many of 

 the adult ticks were put together. Previously many egg masses 

 had %een kept too dry, presumably on account of atmospheric con- 

 ditions and the small number of adults placed in a jar. Later on 

 better conditions were secured by collecting the ticks in paper bags 

 in lots of 200 or 300 and transferring them to the cloth-covered jars 

 when they were nearly hatched. 



These methods caused the numbers of seed ticks occurring on the 

 cattle to be purely guesswork. Failure resulted in spite of special 

 efforts to infest those cattle that presented the fewest adult ticks. 

 Such were nearly immune to ticks. 



RESULTS OF EXPERIMENTS. 



The damage done to the infested cows by the ticks seems to have 

 arisen from two distinct causes; first, a fever incited in some of the 

 cattle at various periods, and, second, loss of blood abstracted by 

 the growing tick. 



FEVER CAUSED BY THE TICKS. 



The presence of fever on various dates is shown in Table 2, where 

 temperatures of both tick-infested and tick-free cows are shown. 

 No attempt was made to take daily temperatures, as the matter of 

 taking any temperatures at all was an afterthought rather than part 

 of the plan. One set of temperatures was taken at 9 a. m. ; all others 

 at 4 p. m. The temperatures of the tick-infested cattle were higher 

 than the checks and nearly always above normal. The temperatures 

 of the tick-free cattle were also often above normal. This may have 

 been due to moist, hot conditions of the atmosphere, since only in 

 exceptional cases were the temperatures abnormal on cool days. 



