F. C. Blshopp and H. P. Wood 
173 
seems to be a slightly larger number of females than .males, this being 
especially notable in ticks which moult to the adult stage off the host. 
As shown in Table V, the proportion of males to females is about 
1 to 3. 
The emergence of the adults from the nymphal exuviae is very 
similar to that observed in the first moult. The exuviae often remain 
attached to the host for some time. The adults, after freeing' them- 
selves from the nymphal skin, usually crawl some distance before 
becoming reattached. They have been seen to detach themselves and 
crawl about a number of times before they settle down for engorgement. 
When newly emerged the adults are soft and pale, the white mark¬ 
ings being indistinct, and the actions of the tick are awkward. The 
size of the adults varies considerably, dependent, in part at least, on 
the food supply of the nymphs. One of the largest males we have 
seen measured 5'9 mm. in length (including capitulum), by 4'5 mm. in 
width, by T2 mm. in thickness. 
One female, in a lot of ticks collected as unengorged adults in 
Oregon and placed on an ox March 29, 1910, at Dallas, Texas, dropped 
off its host fully engorged on April 7, or the ninth day after attachment. 
Other adults placed on hosts under similar circumstances were only 
partially engorged after being attached for much longer periods. 
Females which became adult on hosts were observed to engorge and 
drop off on the eighth day after reaching the adult stage (see Table VI). 
The maximum time required for engorgement is difficult to determine, 
due to the successive moulting of nymphs to adults. The longest time 
a female has been observed to remain on a host was 30 days. The 
bodies of the males become considerably thickened during feeding, and 
they, as well as the females, exude numerous drops of excrement as 
long as they remain on the host. 
The engorged females (PI. XI, tigs. 5, 6) usually have a distinct 
olive-green tint dorsally and are more slate coloured ventrally. The 
size varies considerably. The ticks engorged experimentally on small 
mammals are usually smaller than those from horses and cattle. Fully 
engorged specimens range in size from 8 - 9 mm. in length (including 
capitulum), by 6'3 mm. in width, by 3’9 mm. in thickness, to 13 - 8 by 9 
by 5'2 mm. 
Pairing of the sexes begins from the fourth to the thirteenth day 
after the first adults appear. The male seeks the female and crawls 
beneath her so that their venters are in apposition. During copulation 
the legs of the male closely clasp the body of the female. Sometimes 
