32 



CIRCULAR 884, U. S. DEPARTMENT OF AGRICULTURE 



Figure 15. — How to use runway probe: A, Right way, forcing probe into main run- 

 way just deep enough to make an opening and to avoid punching a hole in the 

 floor: B. wrong way, placing bait in a side runway; (.. placing bait correctly. 



COST AND RETURNS FROM CONTROL 



A measure of the value of pocket gopher control as a range-improve- 

 ment practice is obtained by comparing the cost of control with the 

 value of the increased forage yield. The results obtained in this study, 

 in which plots were maintained virtually 100 percent gopher-free by 

 treatment twice each year, and by trapping to remove persistent indi- 

 viduals, are not entirely comparable to results that would be obtained 

 from gopher-control projects. They do serve, however, as a guide to 

 what can be expected from control measures. 



Control on a project basis, with an efficient crew and thorough treat- 

 ment of an area, should give at least a 90-percent kill of gophers. This 

 should be followed by maintenance treatment each year, at about 10 

 percent of the cost of the first treatment, until the effect of the gopher is 

 overcome. Obviously, poisoning an area and then allowing repopulation 

 of the gophers by failing to carry out any subsequent measures would 

 not be effective control. 



Recent estimates of costs for large-scale gopher control projects are 

 not available, because there have been none since World War II. Based 

 on records of earlier projects, present costs of control in the most acces- 

 sible areas having moderate gopher populations are estimated to be 

 about 40 cents per acre. However, costs vary considerably between areas 

 because of such factors as accessibility and population density. Under 

 heavy infestation and other conditions, costs may be increased several 

 times. 



