182 
Biology of Dermacentor 
11, 1911, began ovipositing on April 11, 1912, or 123 days after drop¬ 
ping off. Only 917 eggs were deposited by this female and oviposition 
continued 20 days. On the first and second days 106 eggs were laid 
and oviposition proceeded as follows on subsequent days : 10, 88, 34, 46, 
24, 86 (2 days), 76, 75, 36, 58, 34, 79, 56, 48, 30, 11, 20. In each case 
the females died within a few days after oviposition was complete. 
Counts were made daily of the eggs deposited by three other females. 
The first of these dropped off (fully engorged) a bovine host on 
November 1, 1912, began depositing April 8, 1913, or 158 days after 
dropping off, and deposited until May 18, or 41 days. During this 
period 2099 eggs were deposited. The second female dropped off a 
bovine host on November 4, 1912, and began depositing on March 31, 
1913, or 116 days after dropping off its host and deposited 1914 eggs 
during the succeeding 49 days. The third individual dropped off a 
bovine host November 9, 1912, began depositing April 1, 1913, and 
deposited 2054 eggs during a period of 49 days. 
The Eggs are oval in shape and yellowish-brown in colour. For 
some time before hatching, the legs and other structures can be clearly 
made out through the shell. As with other Ixodid ticks, the length of 
the incubation period depends on the temperature and humidity. The 
percentage of hatching is usually much higher in large, than in small 
masses of eggs. 
As shown in Table VII, the incubation period varied from 37 to 55 
days when the eggs were kept in the laboratory. 
TABLE VII. Incubation of Dermacentor higrolineatus in the 
laboratory at Dallas, Texas. 
Temperature during incubation 
Eggs deposited 
Number 
of eggs 
Hatching 
began 
Incubation 
period 
max. 
min. 
average daily 
mean 
1912 
1912 
(days) 
° F. 
°F. 
° 
April 1 
2700 
May 26 
55 
950 
48-5 
73-7 
„ 11 
2800 
„ 29 
48 
96-0 
53-0 
76-3 
„ 11 
122 
„ 30 
49 
96-0 
530 
76-5 
„ 11 
132 
„ 30 
46 
960 
53-0 
76-6 
„ 11 
162 
„ 30 
46 
96 0 
53-0 
76-6 
22 
11 " l “ J 
„ 30 
49 
960 
58 0 
76-0 
„ 23 
500 
„ 30 
37 
96-0 
59'5 
78-2 
The Larva (PL XII, figs. 1-2): Wheu first hatched the larvae are 
pale and sluggish. As they harden they become brownish-yellow and 
move about, but soon settle down in masses and remain quiet for long 
