164 LIFE HISTORY OF NORTH AMERICAN TICKS. 
They have been found to mate within a day or two and to continue 
in this relation for a number of days or until the females dropped. As 
many as three-fourths of the individuals collected in western Texas 
were found paired. In one instance a male was found paired with a 
female of Dermacentor variabilis. After the dropping of the female 
with which it had mated, one male was observed mated with a female 
of M. annulatus. It remained in this relation until it was removed 
from the host a week later. 
About 30 lots of this species have been collected by agents of the 
bureau. In only two instances were any engorged females found. 
Engorgement of females that were removed from rabbits took place 
upon bovine hosts in 12 days. A female which was placed upon a 
tame rabbit with a male on May 25, 1910, did not show any sign of 
engorging until 10 days later, when it was observed in copulation. 
Engorgement began on the third day following mating, but the date 
of dropping of this individual was not recorded. The females, during 
engorgement, excrete large quantities of material which when dry 
resembles coagulated blood. This frequently incrusts the male which 
is beneath the female, thus rendering him helpless and sometimes 
actually killing him. 
The ear of the rabbit, both inside and outside, appears to be pre- 
ferred as a place for attachment. The large number of males that 
have been taken from rabbits is sufficient evidence that they remain 
upon the host for a long period after the females have dropped. 
TaBLE LXXV ees al 0 of females of Dermacentor parumapertus marginatus, 
| 
| | Females sae 
Adults applied. Host. | dropped Period of attach- Size engorged. 
| engorged. 
Days. 
UNG S LN eee eee ee Ne sacs = Bovine....| June 21, 1908 13 | 10 by 7 by 4mm. 
June 29, 1908.2... 52 b thoes Agar sche cease Gorst . July 11,1908 12 | 11 by 8.5 by 5 mm. 
WO cp tee teae ae eee ees orale do....| July 14,1908 15 | 12.5 by 9 by 6.5 mm 
Julyit, P0082 52.2. 5552 ea set 2-3 ee dozss22 July 19,1908 12 | 12 by 8.5 by 6 mm. 
DO se ccctas te nas watarsra elataress Jocees do.-ea. July 21,1908 14] 11 by 7.5 by 4mm. 
DWOde Sea.b- teat se. Seeds. ese dostts4 July 25,1908 18 | 10 by 7 by 5 mm. 
DG eee shan setae races {eae do.....| Aug. 2,1908 26 | 10 by 7 by 3.5 mm 
AE 27 LOUBAS SS este 325. T3k ne GOR ES: Sept. 5,1908 | (Sloughed off.) 9 | 10 by 7 by 4.5mm 
Sie 25, 000022. a. eee | be dots July 7,1909 12 
LIFE CYCLE. 
Larve may live as long as 227 days; they engorge as soon as 4 days 
after application and may molt in 8 days after dropping, a total 
effective temperature of 350° F. being required. 
Nymphs may live as long as 175 days; they may engorge in 4 days 
after application and molt as soon as 21 days after dropping, a total 
effective temperature of 641° F. being required. 
Adults have been found to live for more than 115 days. Mating 
takes place on the host. Females may engorge as soon as 12 days 
after being put on a host; they may begin oviposition as soon as 5 
days after dropping and deposit as many as 4,660 eggs. Deposition 
may continue for 26 days. Embryonic development may be com- 
