19101 Rucker, California Ground Squirrel and Bubonic Plague. 143 



the Acalanes Grant I saw a prune orchard, in which at least 30% 

 of the crop had been destroyed by these subterranean thieves. It 

 is therefore quite as important from an economic standpoint as 

 from the aspect of the protection of the public health 'that this 

 species die. 



This means a large expenditure of money. Two million dol- 

 lars is a conservative estimate. It means that a large number of 

 men must be employed so that a vast area may be made the object 

 of a simultaneous attack. The best season of the year is during 

 the rainy months, when food is relatively scarce and the ground 

 is moist enough to hold the fumes of carbon bisulphide. This 

 latter agent has been found very efficacious and is employed by * 

 soaking a ball of waste the size of an orange with the chemical. 

 The charge is then thrust into the hole, which is closed by sod, and 

 the gas being heavier than air it sinks into the uttermost recesses 

 of the tunnel. Another way, and quite as efficacious, consists in 

 the explosion of the charge. The squirrels are stunned by the de- 

 tonation, and subsequently asphyxiated by the large quantities of 

 sulphur dioxide, sulphur monoxide, hydrosulphurous acid, and 

 various other gases which are generated. Experiments have also 

 been made to determine the value of poisons to be used. Taken into 

 the alimentary canal strychnine is especially lethal. It is an inter- 

 esting fact that the squirrels will stand more strychnine in their 

 stomachs than they will in their cheek pouches, and inasmuch as 

 they carry the grain to the burrows in their cheek pouches, it is 

 in this way that they are killed. The best medium for such a 

 poison has been found to be barley, one of its chief advantages 

 being the fact that it is not so readily taken by birds as wheat and 

 other grains. There are several ways of applying the strychnine 

 to the barley, either in a menstrum of starch paste or a mixture of 

 honey and eggs. Experiments have been made with both means, 

 and there seems to be little choice between them. 



It is believed that when the large exterminating campaign is 

 begun, the co-operation of the individual land holder can be se- 

 cured, but it should be borne in mind that there are large areas 

 of wild land which at present are not under cultivation, being used 

 chiefly for the grazing of cattle. It is in these regions that the 

 hardest part of the fight must occur. Such a campaign will be an 

 enormous undertaking, but it must come, and not until it has 



