14 



FARMEES BULLETIN 932. 



grain, and within its range warfare against it is absolutely neces- 

 sary to successful farming. 



The striped ground squirrel, 1 the Franklin ground squirrel, 2 and 

 some other species, which are less gregarious and seldom occur in 

 great numbers in any locality, are less destructive than any of the 

 three groups named. Other species are nearly as injurious as those 

 described. The animals have been dealt with in three groups, because 

 slightly different formulas for poisoning each of them have been 

 worked out by field investigators of the Biological Survey. The 



Bl I 148 



FIG. 10. Break in irrigation ditch (lateral) caused by burrowing of California ground 

 squirrel. Six acres of alfalfa ruined. 



formula for the Richardson ground squirrel is adapted for all the 

 species except the Columbia and the California forms. 



Poison for Columbia ground squirrels. Mix 1 ounce of powdered strychnin 

 (alkaloid), 1 ounce of powdered bicarbonate of soda, 1 teaspoonful of saccharin, 

 and pound of dry powdered laundry starch, and stir with enough cold water 

 to make a smooth, creamy paste. Apply to 12 quarts of good, clean oats in a 

 metal tub or other vessel, and stir thoroughly to distribute the poison evenly. 

 When the poisoned grain is dry scatter it along squirrel trails or on hard soil 

 on the surface near the squirrel burrows. A quart of the grain should make 

 40 to 50 baits, and if properly distributed stock will not be endangered by this 

 quantity. 



1 Citellus trideccmlincatus, including several races. 



2 Citcllus franklini. 



