Some of the More Important Ticks of the United

In recent years considerable attention has been attracted to the tick which transmits splenetic fever of cattle, known as the North American Jever tick. The import/ince of this tick as the sole transmitter of the disease in nature has become common knowledge, at least in the South. As a matter of fact, this tick is of much greater importance than any other species occurring in the United States. Nevertheless there are other forms which should be considered. One species, for instance, transmits a serious disease of human beings which is spread over an extensive region and causes the loss of a considerable number of human lives each year. As in the case of the cattle disease, the human disease, known as Eocky Mountain spotted fever, is transmitted only through the attack of a tick, and the plan that is being followed in dealing with the cattle disease would apply in the case of the human disease ; that is, the eradication of the tick would result in the eradication of the disease. Although ticks are attracting more attention at the present time as transmitters of diseases than in other ways, they are of considerable importance as parasites of domestic animals. Their presence always results in irritation and the loss of blood. The consequence is that the infested animals frequently fail to make proper returns for the expense incurred in feeding, and in some instances the attack is so severe that death follows. (See PI. XV, fig. 1.) The object of the present paper is to point out some of the species of ticks occurring in the United States which are of importance either as transmitters of disease or otherwise. It will be noted that in several cases where diseases are not known to be transmitted at present, future investigation may possibly connect the ticks with certain maladies. It is thus very probable that increased knowledge of ticks will show a degree of importance which is not now realized. All ticks occur in four stages, namely, egg, larva or seed tick, nymph, and adult. The ticks usually seen are adults, in which stage there are, of course, males and females. The females, however, increase greatly in size on account of the engorgement of blood; the males are consequently inconspicuous and generally overlooked, being