164 The Rocky Mountain Locust. 



Where oil has been scarce, some persons have substituted 

 concentrated lye, but when used strong enough to kill, it 

 costs about as much as the oil. The oil-pans can be used 

 only when the crops to be protected are small. 



Small pans for oil, attached to an obliquing pole or 

 handle, do excellent service in gardens. 



[Fig. 36.] 



Large Coal-oil Pan. 



Coal tar may also be used to good advantage in similar 

 pans, either drawn or pushed by man or horse. 



Mr. Rufus Clark, of Denver, uses apiece of oil cloth, nine 

 to twelve feet long, and six feet wide ; one side and each 

 end are secured to light wooden strips by common carpet 

 tacks, and the corners strengthened by braces. 



" The oil cloth is smeared with coal tar, purchased at the 

 Denver Gas Works for $7.50 per barrel, and the trap is 

 dragged over the ground by two men — a cord about ten 

 feet long being fastened to the front corners for that purpose. 

 The entire expense of the " trap " is about $3.50, and as it 

 is light and easily handled, will be found serviceable on 

 small as well as large farms." 



Zinc instead of oil cloth has also been used for the same 

 purpose. 



The experience of 1875 showed that when the insects 



