62 LIFE HISTORY OF NORTH AMERICAN TICKS. 
DESCRIPTIVE. 
Adult (P1. IV, figs. 6-9).—Female 5 by 3.5 by 2.5 mm. to 10 by 6 
by 3.5 mm. Male usually somewhat smaller than the female. The 
adults are grayish to dark brown in color. 
Nymph (Pl. IV, figs. 2-5).—Unengorged, 2.25 by 1.5 mm. to 3 by 
2mm.; engorged, 7 by 4 by 2 mm. to 8 by 5 by 3 mm. — The body of 
nymphs as they emerge from the larval skin have a blood-red color 
extending to the first two segments of the legs; otherwise they are a 
pearly white. Soon, however, they turn to a reddish brown. 
Larva (Pl. IV, fig. 1)—Unengorged, about 0.55 by 0.30 mm.; 
engorged, 3 by 2mm. to 4 by 2.5mm. The seed ticks are dark gray 
in color, turning to a pink, then to a whitish color as they engorge. 
Egg.—Spherical, dark brown, shining, smooth. The average size 
of 10 specimens measured was 0.480 by 0.456 mm. 
HOST RELATIONSHIP. 
It is the habit of this tick to attach in the ears of the host, deep 
down in the folds of the concha and frequently in the external meatus. 
This habit appears to be more or less of an adaptation for protection, 
since they can not be removed by the host, or picked off by birds, 
and are not exposed to the attack of parasites. 
The species was described from specimens taken from the ears of 
Mexican horses. Though collected more frequently from cattle than 
from any other host, it appears to attach to any of the larger mam- 
mals with which it comes in contact. In collections made in Texas 
and neighboring States by agents of the Bureau of Entomology up to 
January, 1911, 53 lots were from cattle, 11 from horses, 10 from dogs, 
8 from cats, 3 from asses, 2 from mules, 2 from man, and 1 each 
from sheep and hog. It has been taken by Mr. H. S. Barber in Cali- 
fornia from the black-tailed deer. 
GEOGRAPHICAL DISTRIBUTION. 
Pe 
(Fig. 2.) 
This tick was originally described by Dugés from Guanajuato, 
Mex., where it is said to be very abundant. We have found it to be 
a very important tick in certain parts of Texas, New Mexico, Arizona, 
California, and Mexico. Owing to the fact that it remains attached 
for long periods it may be widely disseminated on cattle, horses, and 
other animals shipped from an infested district. This fact doubtless 
accounts for some of the records from northern States. Up to the 
present time we have authentic records of its collection from the 
States of Kentucky, Iowa, Nebraska, Kansas, Oklahoma, Oregon, 
New Mexico, Idaho, Nevada, Arizona, California, Colorado, Texas, 
Louisiana, and Utah. The species was found in abundance by 
