444 SANITARY ENTOJNIOLOGY 



somewhat more resistant to arsenical dips than the cattle tick, and it 

 was found best to add kerosene emulsion to the arsenical, following the 

 Watkins-Pitchford formula. In order to prevent the dropping of replete 

 females, the dipping must be practiced at weekly intervals. Fortunately 

 the spotted fever tick confines its activity in the adult stage to the spring 

 months, so that it is not necessar}' to continue tlie dipping later than 

 about the first of Jul3\ 



Since practically all of the immature stages of this species develop 

 on small rodents, notably the ground squirrels, wood rats, pine squirrels, 

 rabbits, etc., the importance of rodent destruction, both from the stand- 

 point of tick control and protection of crops, is apparent. In much of 

 the territory where the spotted fever tick abounds, it is, however, impracti- 

 cable to reduce tlie number of rodents to a very low point. In other 

 words, in the scheme of eradication dipping of live stock should come 

 first and the destruction of rodents be taken up as a secondary step. 



Aside from the destruction of this tick on animals, it is necessary for 

 man to protect himself against its attack. This can be accomplished to 

 some extent by avoiding cut-over woodlands or brushy areas, by wearing 

 clothing calculated to exclude the ticks and by examination of one's 

 person at frequent intervals. It was found by Dr. Ricketts that a tick 

 must be attached to a guinea pig for one hour or longer to produce the 

 disease, thus it would seem that there is little danger of infection in man 

 if the ticks are removed promptly. Since no successful remedy for the 

 treatment or prevention of the disease has been devised, the importance 

 of exercising care in preventing infection by keeping free of ticks can not 

 be too strongly emphasized. 



The Spinose Ear Tick. — We are concerned with this species both on 

 account of its injurious effect on horses, cattle, dogs, and other animals, 

 and the frequency of its attachment in the ears of man. Furthermore we 

 should be familiar with this tick since a considerable part of our military 

 activities in this country have been and will probably continue to be in 

 the Southwest where the species abounds. 



It is probable that by exercising some care in locating camps and in 

 choosing places for sleeping, some degree of immunity from attack will 

 result. The seed ticks are, of course, concentrated about feed lots, 

 corrals and watering places of live stock and these should be avoided in 

 choosing a camp site. 



The effect on animals of heavy infestations of this species is very 

 marked. The ears are droopy, the hair rough and the animal presents 

 an unthrifty appearance. Fattening is difficult if not impossible, and 

 under range conditions the loss by death is not infrequent. In horses and 

 mules there is a marked shyness on the part of the animals when attempt 

 is made to touch the ears or put on a bridle. This is sometimes so extreme 



