20 THE ROCKY MOUNTAIN SPOTTED FEVER TICK. 
inactive. They soon become dried out and the external structures 
become thoroughly hardened. The color pattern becomes more pro- 
nounced and activity increases. This is the stage in which the ticks 
are ordinarily observed in the spring months. The males (PL II, 
figs. 2, 4) and females (PL II, figs. 1, 3) are nearly the same size, but 
the former have a hard plate or shield covering the entire back. 
Upon this shield is a somewhat complicated pattern formed by white 
bands or stripes. In the female the shield is much smaller, covering 
only the anterior portion of the body. Almost its entire surface is 
covered with white. The portion of the body of the female behind 
the shield is rather soft and elastic. It is usually somewhat wrinkled 
and of a dark reddish-brown color. In this stage, as well as in the 
preceding, the ticks have eight legs, but the white markings on the 
backs of both sexes and the presence of a small genital opening on the 
underside near the "heads" of the ticks serve to distinguish them 
readily from the other stages. Of course the size of the adult ticks is 
considerably greater than that of either of the immature stages. 
Prior to feeding they usually measure about one-sixth of an inch in 
length by one-tenth of an inch in width. 
Before reproduction can begin it is necessary for both the males 
and females to feed upon the blood of some animal. They usually 
attach to the large domestic animals, and after feeding about 4 
days or more the males start in search of mates. Fertilization takes 
place on the host, and in from 8 to 14 days after attachment the 
females, having become filled with blood, drop from the host and 
seek a protected place in which to deposit their eggs. During the 
course of feeding the portion of the body of the female behind the 
shield is greatly distended, so that the specimens now measure about 
one-half inch long by one-third inch wide by one-fourth inch thick. 
On account of the enormous distention of the back part of the 
bodjr of the female, the legs and head are rendered inconspicuous. 
A close examination, however, will show the white shield on the 
back just behind the "head." When the females are filled with 
blood the back part of the body is usually a bluish-gray color. 
Although the males imbibe a certain amount of blood when attached 
to an animal they never increase greatly in size as do the females. 
The females always drop from the host animal before beginning 
the deposition of eggs. Deposition continues for about 30 days, 
during which time several thousand eggs are deposited. (See PL II, 
fig. 5.) During the process of deposition the female gradually 
shrinks in size. When all of the eggs are expelled the tick is much 
shriveled (PL III, fig. 1) and has changed in color to a mottled yel- 
lowish. She dies within a few days after the last eggs are deposited. 
While depositing her eggs the female remains in the same place, 
so that all of the eggs are in one large mass. The eggs hatch into 
seed ticks in from 16 to 51 days and the life cycle is again repeated. 
