SEASONAL HISTORY AND HABITS. 
28 
During the summer months we have found that all of the seed ticks 
hatching from a mass of eggs usually die within one month after 
=} ta) 
the first eggs hatch. In one instance a period of 117 days elapsed 
between the beginning of hatching of the eggs and the death of the 
t=} > oS t 
last seed tick. This is the greatest longevity which we have observed. 
Table II indicates the variations in the time required for the be- 
ginning of egg laying, incubation of the eggs, and length of time 
required for the starvation of the seed ticks: 
TABLE II.—Time required for beginning of deposition of eggs, hatching, and 
starvation of seed ticks of Dermacentor venustus. 
Period Period Period 
ed from drop- from be- Date | from be- ere 
famiale Date first ping of | phate hatching| Simning of| all seed | ginning of ‘erie 
dropped or eggs were de- | female to of eggs began. deposition ticks | hatching to rei ee. din 
was picked posited beginning *| to begin- were death of ine 
from host of de- ning of dead. last seed cubation 
F position. hatching. tick. si 5 
Days. Days. Days. Mp 
June 11,1909 | June 27,1909 16 | July 15,1909 18 | Sept. 5 52 91.8 
Mar. 28,1910} Apr. 7,1910 10 | May 10,1910 33 | July 25 76 70. 49 
Apr. 2,1910! | May 13,1910 41 | July 3,1910 51 | Aug. 1 BO) Ea Beare 
Apr. 7,1910 } Apr. 17,1910 10 | May 19,1910 32 | July 19 61 74.6 
Apr. 13,1910 | Apr. 20,1910 7 | May 25,1910 35 | Aug. 15 82 71. 78 
Apr. 26,1910} May 2,1910 6 | May 31,1910 29 | July 30 60 71.55 
May 1,1910! | May 19,1910 18 | July 9,1910 51 | Sept. 3 il FEB aeeees see 
May 14,1910 | May 23,1910 9 | June 12,1910 20 | Aug. 31 80 79. 64 
May — 1910! j..... doteeeeeelo =. sees see July 9,1910 47 | Nov. 3 DG ELE cactincess 
June 4,1910 | June 13,1910 9 | June 29,1910 16 | Sept. 29 92 84. 37 
June 4,1910! | June 17,1910 13 ql 2 34 | Aug. 11 7 il ee eee 
efore 
July 16,1910 | July 25,1910 9 | Aug. 10,1910 16 | Sept. 30 51 84. 59 
1 These records were made in the Bitter Root Valley in Montana; all others were made at Dallas, Tex. 
Those larvee which succeed in finding an animal upon which to 
engorge usually attach about the head and ears of the host, be- 
come filled with blood, and drop from the animal between the 
third and eighth days. In nature the larve feed almost entirely 
upon the small wild mammals, although experimentally they have 
been forced to engorge upon cattle. As has been stated, the larvee 
after becoming engorged drop from the animal, find a protected 
place, shed their skins, and become active eight-legged creatures 
known as nymphs. These nymphs emerge from the quiescent seed- 
tick stage from about the middle of July to the beginning of cold 
weather. Some of those transforming during the summer find 
hosts, become engorged, and drop for molting. A few of these 
probably molt to adults before cold weather begins and hibernation 
takes place in the adult stage. These few individuals are the only 
ones which complete their life cycle in a single season. It should 
be emphasized that these nymphs, as well as the seed ticks, feed 
almost exclusively on small wild mammals. Tables ITI and IV show 
the length of the engorgement and molting periods of larve and 
nymphs. 
