202 LIFE HISTORY OF NORTH AMERICAN TICKS. 
days after it had been collected from an equine and placed upon the 
bovine. It detached and escaped from the bag at the end of this 
time. i 
A peculiar habit which is especially noticeable in this species is 
that of the excretion, by the female during engorgement, of large 
quantities of a substance which when dry resembles coagulated blood. 
This habit, while particularly noticeable in the members of the genus 
Dermacentor, is most pronounced in this species. It is a frequent 
occurrence for the male to get incrusted in the excreta and, being 
unable to extricate himself, to perish. It is this habit of voiding large 
quantities of excrement that increases to some extent the economic 
importance of this tick. 
PARASITIC PERIOD. 
The parasitic cycle of three lots was followed upon bovines at the 
laboratory. Two of these lots were placed upon the scrotum of the 
host and the third in the ear. 
On April 10, 1908, numerous larvee were placed on the scrotum 
of a bull; 2 molted to nymphs on April 23, 2 on April 24, and 1 on 
April 25, or the thirteenth, fourteenth, and fifteenth days, respectively, 
after application. On May 4, 1 molted to a female; May 6, 1 molted 
to a female; and May 19, 2 molted to females; or the twenty-fourth, 
twenty-sixth, and twenty-ninth days after application. As no males 
were present the females were not fertilized and they only partially 
engorged. A second lot of larvee was applied to the scrotum of a bull 
on April 18, 1908. They began to molt on the ninth day and molted 
as follows: April 27, 3; April 28, 6; April 29, 2; April 30, 1. On 
May 5, the seventeenth day after application, 1 nymph molted to a 
male, and molting continued as follows: May 6, 1 male, 1 female; 
May 7, 1, and from May 9 to 11, 1 molted each day, and on May 13, 2 
molted, the sex of the last mentioned not being recorded. The first 
engorged female dropped on May 17, or 29 days after attachment as a 
larva. Others dropped engorged on July 18, 19, and 20; 2 on July 22, 
and the last on July 26, or 38 days after having attached as a larva. 
A third lot of larvee was applied to the ear of a host on July 1, 
1908. They began to molt 8 days later (July 9), many having molted 
by the ninth day and all by the eleventh. Many nymphs were fully 
engorged on July 14, but did not molt until the seventeenth day (July 
18), when 2 males and 2 females appeared; all had molted by the 
following day. Three females dropped engorged on July 27, the 
twenty-sixth day from attachment; a partially engorged female was 
crushed on July 29 and the last female was missing on August 11, 
after having remained mated with a male for 10 days. 
