18(3 
Biology of Dermacentor 
of the neck where the hair was longer. This may have been caused by 
a rather sudden drop in the temperature or by a tendency of the adults 
to seek the protection of longer hair before engorging. The females 
when well engorged often easily become detached if touched. 
Summary of non-parasitic 'period: The preoviposition period 
ranges from 122 to 161 days, the oviposition period from 20 to 36 days; 
the incubation period from 37 to 55 days; the larval longevity from 72 
to at least 166 days; and the total non-parasitic period—from the 
dropping of the engorged females to the death of the last larva—from 
243 to at least 360 days. Some of these data are given in more detail 
in Table VIII. 
Economic Importance. 
D. nigrolineatus appears to be of little general economic importance 
although locally it sometimes infests cattle sufficiently to greatly 
reduce their flesh and vitality. The only locality in which we know of 
its occurrence as a pest is near Lake, Fentress County, Tennessee. In 
this district, which is hilly and timbered, the ticks are often found in 
great numbers on the cattle when they are brought in from the range 
in the autumn. The backs and hindquarters of the animals are usually 
the most heavily infested, and certain animals bear far greater numbers 
of ticks than others in the same herd. 
Although this tick is sometimes found in numbers on deer, it is not 
known to become numerous enough to cause any particular injury to 
them. 
DESCRIPTION OF PLATES X TO XII. 
PLATE X. 
Figs. 1-4. Dermacentor hunteri. (Photographs by G. N.- Wolcott.) 
Fig. 1. Unengorged female, dorsal view. 
Fig. 2. Unengorged female, ventral view. 
Fig. 3. Male, dorsal view. 
Fig. 4. Male, ventral view. 
Figs. 5-7. Dermacentor albipictus. (Photographs by H. P. Wood.) 
Fig. 5. Male stigmal plate (right). 
Fig. 6. Female stigmal plate (left). 
Fig. 7. Spermatophore as left by male after spermatozoa had been pressed out. 
Figs. 8-11. Dermacentor nigrolineatus. (Photographs by H. P. Wood.) 
Fig. 8. Female stigmal plate (right). 
Fig. 9. Male stigmal plate (left). 
Fig. 10. Engorged nymph, dorsal view. 
Fig. 11. Engorged nymph, ventral view. 
