THE BROWN DOG TICK. 103 
DESCRIPTIVE. 
Adult (Pl. VI, figs. 13-17).—Males from 2 by 1.25 to 3 by 1.5 
mm. Females, unengorged, 1.5 by 1 mm. to 3 by 1.75 mm.; engorged, 
6 by 4 by 1.5 mm. to 11 by 7 by 4.5mm. The males and females are 
reddish brown, without markings, the legs being somewhat paler. 
Nymph (Pl. VI, fig. 12)—Unengorged, about 0.94 by 0.57 mm.; 
engorged, 2.5 by 1.5 by 1 mm. to 3.5 by 2 by 1 mm. Color, unen- 
gorged, reddish brown; engorged, dark gray, some with a pink tinge 
and many whitish due to the engorgement of lymph; smooth, shining. 
Capitulum 0.244 mm. long (from tip of hypostome to base of emar- 
gination of scutum); scutum 0.451 mm. long by 0.462 mm. wide. 
Larva (Pl. VI, figs. 10, 11)—Unengorged, about 0.457 by 0.328 
mm.; engorged, about 1.5 by 0.88 mm. Color, unengorged, light 
brown; engorged, dark gray; capitulum 0.116 mm. long (from tip 
of hypostome to base of emargination of scutum); scutum 0.212 mm. 
long by 0.301 mm. wide. 
Egg.—The average size of 10 eggs was 0.43 by 0.37 mm.; ellip- 
soidal, dark brown, shining, smooth. 
HOST RELATIONSHIP. 
Although this tick infests principally the dog it appears to attach 
to numerous hosts, among which the following have been reported: 
Fox, and ‘other canines, cat, ox, horse, hare, dromedary, camel, 
sheep, goat, birds, and also one or two species of reptiles. 
In extensive collections made by agents of this bureau in Texas 
and Mexico, however, the species has been taken from the dog only. 
Newstead reports that in Jamaica it is common on the ox as well as 
the dog and that it was also found on the horse. In one instance two 
slightly engorged nymphs attached between the fingers of one hand of 
_ one of the authors after he had been collecting specimens from dogs. 
In regard to the position of attachment, Christophers, as well as 
the writers, has observed that the adults frequently attach to the 
inside of the dog’s ears, even deep down in the meatus. Christophers, 
Nuttall, a correspondent of Newstead, and the writers have observed 
that they frequently attach between the toes and that they may be 
found there in clusters of 3 or 4. The writers have found the females 
to engorge to repletion between the toes of puppies. This position is 
readily accessible to the ticks and infestation may occur without 
being suspected, as even the engorged females are often obscured 
from view. Many larve and nymphs of this as well as other species 
attach and engorge in the little pocket on the posterior border of 
the ear. In the immature stages it appears to prefer to attach in 
the long hair on the neck rather than in the ears, the ticks frequently 
being found in cluster of a dozen or more. All three stages may, 
however, attach to almost any part of the body. 
