10 BULLETIN 45, U. S. DEPAKTMENT OF AGEICULTUEE. 
There would be some very serious objections to using sheep ex- 
clusively in the destruction of ticks, even though they should be found 
to kill practically all the ticks which get on them. In the first place, 
it would be necessary to eliminate all live stock except this on which 
the ticks could be destroyed at weekly intervals by dipping or other- 
wise. Secondly, it is impracticable to stock heavily a given area with 
sheep and attempt to carry the usual number of other live stock on 
the same pastures. It would thus be necessary to reduce greatly the 
number of live stock other than sheep in order to graze a sufficient 
number of sheep to have any appreciable value as collectors of ticks. 
Moreover, it would be necessary to cut down all vegetation higher 
than a sheep's back, for there are many ticks that await a host higher 
than 2 feet from the ground. It would also be necessary to drive the 
sheep where the ticks were known to be located, for the sheep nat- 
urally go w T here the feed is best. In the locality where the experi- 
ment with 20 sheep was carried on it was found that there were few 
ticks where the feed was abundant, but many next to the foothills 
and in the ravines where the feed was scarce. The character of the 
country on the western side of the valley in many places is also such 
that it would not admit of herding sheep. Should sheep run con- 
tinuously in the wooded and brushy country on the western side of 
the valley they would wear off the wool, which would make them 
increasingly more susceptible to tick attack and less profitable to the 
owners. 
The tendency of the tick to attach in bunches would indicate that 
in case ticks obtained a start on any animal they would breed on that 
animal with increasing facility ; for it would be more easy, as the fe- 
males enlarged, for the males to find them. Since most of the en- 
gorged females picked from the sheep in the experiment had males 
beneath them, and all of the females which were removed when well 
engorged deposited eggs which hatched normally, there* appears to be 
little likelihood that there would be many females to drop which 
would not be fertile. 
The possibility that sheep may serve as a reservoir for the virus of 
spotted fever is a point that should be tested before sheep are used 
at all in the destruction of ticks. 
It appears, however, that sheep are very good collectors of ticks. 
Six sheep with heavy wool picked up in 11 days about 72 females 
and 47 males. Although no comparative experiment has been per- 
formed, it is the writer's opinion that 6 horses or 6 cattle under the 
same conditions would not have picked up and retained nearly that 
number. Therefore in " ticky " country which is favorable to the 
herding of sheep it would be advantageous to use sheep as collectors 
of ticks. By dipping the sheep once in 7 days it would seem that 
much good could be accomplished. To bring about the greatest good 
