Cattle-Fever Ticks. 11 



DEVELOPMENT ON CATTLE. 



The parasitic part of a tick's life begins ^Yhen the larva or seed 

 tick reaches a favorable host, such as a cow. The tick crawls up 

 over the hair and commonh- attaches itself to the skin of the es- 

 cutcheon, the inside of the thighs and flanks, or to the dewlap. 

 It begins at once to draw blood and soon increases in size. In a few 

 days the young tick changes from a brown color to white, and in 

 from 5 to 12 days molts or sheds its skin. The new form has 8 

 legs instead of 6 and is Iniown as a nymph. 



In from 5 to 11 days after the first molt the tick again sheds its 

 skin and becomes sexually mature. At this stage for the first time, 

 males and females can be distinguished with certainty. The male 

 emerges from his skin as a brown, oval tick, about one-tenth of an 

 inch long. He has reached his growth and goes through no further 

 development, but later he shows great activity, moving about over 

 the skin of the host. The female at the time of moMing is slightly 

 larger than the male. She never shows much activity, seldom mov- 

 ing far from her original point of attachment. She still has to un- 

 dergo most of her growth. "After mating, the female increases very 

 rapidly in size and has been known to become fully engorged as 

 early as 48 hours after the second molt, but usually at least 4 days 

 are required for her engorgement. Commonly this period lasts from 

 about a week to as long as 25 days. In exceptional cases, the time 

 that elapses betAveen the attachment of the tick as a seed tick and 

 its dropping from the animal as a fully engorged female may be 

 less than 20 days, but generally it is 3 weeks or a little more. 

 The greatest length of time that a tick has been observed to stay 

 on an animal is 66 days. 



SUMMARY OF LIFE HISTORY. 



To sum up, on the pasture there are three stages of the tick — the 

 engorged female, the egg, and the larva or seed tick; and on the 

 host animal are also three stages — the larva or seed tick, the nymph, 

 the sexually mature adult of both sexes, and in addition the engorged 

 condition of the female. 



METHODS OF ERADICATION. 



In undertaking measures for eradicating the tick it is evident 

 that the pest may be attacked in two locations, namely, the pas- 

 ture and the cattle. Animals may be freed of ticks in two ways. 

 They may be treated with a disinfectant that will destroy all the 

 ticks present, or they may be pastured at proper intervals on tick- 

 free fields until all the ticks have dropped. The method of freeing 

 cattle from ticks by applying a solution that kills the ticks is the 



