Ill 



Parker (R. R). The Control of Rocky Mountain Spotted Fever in 

 the Bitter Root Valley.— Montana Stale Bd. But., Bozcman, 

 Circ. 1, March 1919, 23 pp. Revised March 1921, 20 pp. 



The remedial measures for the tick [Dcrmacentor vcnustus] that 

 disseminates Rocky Mountain spotted fever consist of dipping, rodent 

 destruction, quarantine measures, hand-picking of ticks from cattle 

 and horses, tick repellents on stock and the regulation of grazing on 

 unfenced land. The newly-hatched ticks and nymphs feed onty on 

 rodents, their most important host being the ground squirrel, which 

 is much more abundant and more widely distributed than any other 

 rodent. iVdult ticks, within the hmits of control areas, feed almost 

 entirely on horses, cattle and sheep, and are present in dangerous 

 numbers only during the spring and early summer. If, therefore, all 

 ground squirrels could be killed off, or the adults be kept from feeding 

 on the larger domestic animals, the ticks would be practically eradi- 

 cated. Residents in Bitter Root Valley are therefore advised to 

 destroy every rodent possible. Ground squirrels may be trapped, 

 shot, or poisoned, the last being the cheapest and most effective 

 remed^^ The formula recommended contains 8 U.S. quarts of crushed 

 oats, 1 oz. strychnine alkaloid, 1 teaspoonful saccharine, ^ lb. starch, 

 1 oz. sodium bicarbonate, and | to f quart of water. This, when 

 mixed, should be placed on a bare spot at the side of, or just behind, 

 the hole, using one teaspoonful at each spot. By a regulation of the 

 State Board of Entomology, all landowners in tick-infested districts 

 are required to spread the poison over their territory twice during 

 each season, namely, during the first half of April and during the fxrst 

 10 days of June, the poison being obtainable from the Board of Ento- 

 mology Field Station at the cost of materials and preparation. 



The methods by which adult ticks may be prevented from engorging 

 on horses and cattle are the prohibition or control of grazing on infested 

 territory, which results in the starvation of adult ticks, hand-picking, 

 dipping, and the use of repellents. Clearing and burning are of some 

 value as accessory measures. By keeping range animals from tick- 

 infested territory from 1st March until the adult tick season is over, 

 for a period of several successive years, practically 100 per cent, of 

 the adult ticks will be killed by starvation. In places where grazing 

 is the only remedial measure, five years would be the minimum time 

 possible for eradication, a longer period giving decidedly more satis- 

 factory results. Wliere both grazing and rodent destruction are 

 practised (the latter being thoroughly undertaken early in the spring) 

 a fair degree of control should be expected in three years. Indis- 

 criminate grazing on unfenced foot-hill areas is a constant source of 

 infestation, but experience has shown that this cannot be entirely 

 prohibited without hardships in some cases. It is, however, being 

 restricted to certain portions, and roadside grazing is prohibited. 

 Owners of dairy stock, work horses, etc., are required to free them 

 of ticks by hand-picking at least once each week and to destroy the 

 ticks. General compulsory dipping has been stopped for various 

 reasons, but the dipping vats are filled each spring and stock-owners 

 are urged to use them. As repellents, raw linseed and raw cottonseed 

 oils, particularly the latter, have proved the most successful, but the 

 real value of this method can only be proved by further experience. 



Quarantine regulations are in force in each district included in the 

 tick control scheme from 1st March to 15th July of each year, during 

 which time the entrance or exit of horses, cows, mules, sheep and 



