LIFE HISTORY OF CATTLE TIOK. 17 
In the manner described a mass of eggs grows steadily in front of 
the tick, while its body becomes correspondingly smaller as the 
process proceeds. The gummy secretion holds the eggs together so 
that the mass looks not unlike a large accumulation of minute brown 
beads. 
The number of eggs deposited varies greatly with the size of the 
female. The highest number recorded in our experiments was 3,806.4 
The average of 189 ticks under various conditions was 1911.7, and 
this probably very closely approximates the average under natural 
conditions. The daily average, of course, varies also. The maxi- 
mum is generally reached from 7 to 9 days after deposition begins. 
The highest number for any 24-hour period was 826. The average 
for 20 ticks was 144. 
INCUBATION. 
Most important means of control of the cattle tick depend upon 
taking advantage of the fact that eggs remain on the ground for a 
considerable time before hatching. Provided there are no seed ticks 
present, it is perfectly safe to allow cattle in areas in which ticks may 
be dropped from them, as, for instance, in fields under cultivation 
for one crop season, if the animals are removed before hatching takes 
place. It will be seen that this has an important bearing on the 
process of relieving cattle of ticks by placing them for limited periods 
in different tick-free inclosures. Accordingly we have made an 
especial effort to obtain data regarding the period occupied in incu- 
bation under different conditions and in different seasons. 
In 1905 a number of experiments to determine the length of the 
incubation period were conducted, the eggs being placed in paper 
pill boxes. Subsequent work showed that this arrangement gives 
more rapid development of the embryo than takes place under normal 
conditions. Especially is the period shortened when an abundance 
of moisture is furnished. In these experiments in July and August 
the eggs hatched in from 17 to 21 days, and during September in 
from 25 to 44 days. These results are of value only in showing how 
the incubation period may be shortened under extreme conditions, 
which must rarely or never occur in nature. 
No eggs deposited in October, 1905, hatched before April 10, 1906, 
a period of over 170 days. 
a The greatest number found by H. A. Morgan was 3,198 (La. Agr. Exp. Sta., Bul. 
d1, p. 242), but Newell and Dougherty record 4,124 in one instance (La. Crop Pest 
Comm., Cire. 10, p. 23). 
5795—No. 72-07 
9 
Z 
