METHODS OF DESTROYING TICKS, 37 
ent upon cattle and remains on its host until mature. The spotted 
fever tick, however, drops to the ground twice for the purpose of 
molting and develops through the immature stages upon certain 
rodents and other animals. In the opinion of the Biological Survey 
the extermination of these rodents within reasonable time appears 
to be impracticable because of the necessary expense. The problem 
is even further complicated by the remarkable ability of the fever 
ticks to live for long periods without hosts. As shown in the dis- 
cussion of the longevity of the stages of the spotted fever tick, a 
period of three years, in which horses and cattle were kept out of the 
pastures, would be required before eradication could be brought about. 
This long period renders the so-called starvation plan entirely 
impracticable. ; 
DIPPING. 
Undoubtedly the so-called arsenical dip is the one best adapted 
for use in the Bitter Root Valley. In fact this dip has practically 
displaced all others for the destruction of ticks in various parts of 
the world. Crude oils have been used to a considerable extent in 
some cases. They are more expensive than the arsenical dip and 
dangerous to cattle under some conditions. Serious losses have fol- 
lowed the use of heavy oils in dry regions or where it has been neces- 
sary to drive the cattle any considerable distance after dipping. 
Another advantage that the arsenical dip will be found to have 
over crude oil for the work in the Bitter Root Valley is that it will 
not act as a repellent. When cattle are oiled a portion of the oil 
remains in the hair and upon the skin for several days. This will 
prevent ticks from attaching. In the case of the arsenical dip, how- 
ever, there is very little repellent effect. As the object of the work 
is to kill the ticks rather than to keep them from the animals, the 
more that can be caused to attach the better. 
The formula for the arsenical dip is as follows: 
Nodiunmecanvponate (sale soda") 25 2= eS eee pounds._ 24 
ATSCHIGE OMG CWhELe drsenic) 22 so Be COLEES SS 
DGS fea 22 i A eR Se lee Ee ee gallons_. 2 
ue oue OL nee ae ee Be SS Es a ee ee does =27500 
The preparation of the arsenical dip is described in Farmers’ Bul- 
letin No. 378, Methods of Exterminating the Texas-fever Tick, pre- 
pared by the Bureau of Animal Industry of this department, as 
follows: 
In preparing the dip, a large caldron or galvanized tank is required for heat- 
ing the water in which to dissolve the chemicals. Thirty or forty gallons of 
water should be placed in the caldron or tank and brought to a boil. The 
sodium carbonate is then added and dissolved by stirring. When this is accom- 
plished, the arsenic is added and dissolved in a similar manner. ‘The fire is 
then drawn and the pine tar added slowly in a thin stream and thoroughly 
mixed with the dip by constant stirring. This strong stock solution is diluted 
to make 500 gallons before using. 
