THE GROUND SQUIRRELS OP CALIFORNIA. 



741 



various pumps, blowers or vaporizers a very great saving of material 

 was occasioned. The last mentioned contrivances found their perfec- 

 tion in the U. S. Destructor, invented by Dr. J. D. Long of the U. S. 

 Public Health Service in 1912 1 . Each of the methods of use was 

 accompanied by disadvantages. By the funnel method a great many 

 burrows could be treated in a single day, but with great loss of material, 

 and while the waste-ball plan found a saving in carbon disulphid, it 

 also resulted in slower work; and in the case of the destructor prac- 

 tically no wastage of material was evident, but the length of the time 

 consumed and the number of men required in operating the contrivance 

 nearly made up the difference in added cost for labor. 



It seemed to be a difficult matter to get away from the sulphur fume 

 idea and throughout the years when methods were eagerly sought we 

 note that someone is constantly reverting to the old idea, In 1883 a 

 farmer rigged up an apparatus, the equipment for which, if bought at 

 present war-time prices, would practically bankrupt an average rancher. 

 A large sheet-iron cylinder six feet long and a foot in diameter was 

 rigged up with a flexible hose 12 feet in length at one end and a black- 

 smith's bellows at the other. In the cylinder barnyard litter and 

 straw into . which charges of sulphur were introduced was burned. 

 Fumes were created which could be seen issuing from open burrows 

 at a considerable distance. When the operator of the bellows believed 

 all holes were fuming sufficiently to insure spread of the gases through- 

 out the underground runways the holes were stopped up and the next 

 colony treated. Repetitions of this type of fumigator are often men- 

 tioned in periodicals of the day. Short lengths of rope were cut up, 

 loosened, soaked in melted sulphur, allowed to dry and then lighted in 

 the burrow. The rope burned slowly and produced dead squirrels — 

 which was the result desired. On par with this creation were swabs 

 of old cloth or rags on the end of a stick dipped first in melted sulphur, 

 then coal oil, the latter insuring proper combustion. It was recom- 

 mended that the hole be left open for some time in order that sufficient 

 draft be furnished for a lengthy period of burning. 



The present day forms of sulphur fume producers are sold as ' ' gopher 

 or squirrel balls," or exterminators of different names, usually con- 

 sisting of a slow-burning base such as sawdust or charcoal mixed with 

 sulphur and gunpowder, the latter to promote combustion. Other 

 chemicals are sometimes introduced to make the fumes more irritating. 

 Another form, a cartridge, has gunpowder in slightly larger quantity 

 to make burning more rapid, and generally contains a heavy charge 

 at the base of the cartridge to produce an explosion, forcing the fumes 

 or vapor produced to all ends of the squirrel burrow. The effectiveness 

 of these various products can not be said to be wholly uniform, for in 

 many cases reports are received of their unqualified success as rodent 

 eradicators against reports of failure. It is, of course, a mistake to 

 think of using them with maximum efficiency at any time other than 

 when much moisture is present in the soil ; in other words, the rainy 

 season. Blowers for dry sulphur are now being equipped with a little 

 extension having a burning pan or nozzle for igniting the finely divided 

 particles of sulphur as the sulphur is blown out through the nozzle tube, 



*For details see Circ. 181, Univ. of Calif. Ag. Exp. Sta. 



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