THE GRAY GOPHERS 121 



Tapping irrigation-ditches. Another most 

 serious mischief, in regions depending on irri- 

 gation, is the destruction of ditch-banks. Some- 

 times the animals are forced out of irrigated 

 land and take up new quarters in the dry ditch- 

 banks, or in course of the regular extension of 

 their tunnels a ditch is encountered and the 

 bank is followed in search of a crossing-place. 

 In either case the burrow is almost sure sooner 

 or later to penetrate below the water-line and 

 start a leak that cuts out the bank and empties 

 the ditch. Altogether, it has been estimated by 

 the Biological Survey that the loss due to go- 

 phers in the western United States is not less 

 than a million dollars a month. 



"No animals," the Survey declares, at the 

 same time, "are more easily controlled on a 

 small farm or along ditches than gophers. 

 They are readily trapped or poisoned, and once 

 cleared out of a field others do not come in at 

 once. Their mode of travel, which is princi- 

 pally by extending their burrows, is of ne- 

 cessity slow; and if occasionally caught or 

 poisoned around the edge of fields or along 

 ditches, they can be effectually controlled." 



