EXTERMINATING THE TEXAS-FEVER TICK. 13 
be ample. It will, however, be a wise precaution to make a careful 
examination of the cattle for ticks before placing them in the non- 
infested field they are to occupy. 
During the part of the year from October to January, inclusive, 
the time required for seed ticks to appear after females have dropped 
is much longer than the time necessary for all the ticks to drop from 
cattle. Consequently, if it is desired, the herd may be continued on 
the same field for the required length of time without danger of 
becoming reinfested. 
FREEING BOTH CATTLE AND PASTURES OF TICKS BY THE 
ROTATION METHOD. 
The particular scheme of rotation to be followed on a farm depends 
much on the conditions which have to be met. In figures 8 to 11 
four plans of rotation are represented. In these diagrams no attempt 
has been made to indicate, except in a very rough way, the relative 
size of the fields, since this depends on the number of cattle and on 
various conditions of a more or less local nature. It rests with the 
farmer to select his fields with regard to location and size so as to 
carry out properly and successfully the plan which he adopts. 
The matter of the dissemination of ticks deserves particular attention 
in considering rotation methods. The engorged females which drop 
on a pasture will crawl at most only a few feet. The same may be 
said of the larve or seed ticks. It is possible, however, for seed ticks 
to be passively carried considerable distances at times. Dogs, cats, 
and other animals which ordinarily pass unhindered over farms may 
become covered with seed ticks while gomg through one field, and 
later some of these may be brushed off the animal while passing 
through the herbage of an adjoining field. Even though the danger 
of ticks being spread in this manner is not great, it will be well, when 
practicable, to take precautions against it. 
Again, engorged females, eggs, and seed ticks may be carried by run- 
ning water from a pasture without being injured in any way. The 
danger from this source is probably greatest where there are many 
small streams subject to frequent floods of short duration and on hill- 
sides where the water runs off with great force during heavy rains. 
This will, no doubt, in some localities present a rather serious problem 
in tick eradication. 
Ticks may crawl from the edge of one pasture into an adjoining 
pasture, or engorged females may. drop from the heads of animals 
reaching through a dividing fence. These difficulties are best over- 
come by constructing a double fence with an intervening space of 15 
feet. Such a double fence, if the land does not slope greatly, will 
also greatly reduce the danger of ticks being washed from one pasture 
to the other during rains. 
378 
