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hours to spray an acre of corn six feet high, or four and a half hours 

 per acre of corn averaging ten inches high. 



The profitable use of these tobacco sprays is practically limited to 

 fields of large corn the outer rows of which have become heavily in- 

 fested by chinch-bugs, which thru neglect or accident, have en- 

 tered the corn from adjoining fields of wheat in numbers sufficient if 

 left to themselves to destroy the entire field; and to fields of young 

 corn which have become infested by chinch-bugs of the hibernating 

 generation in early spring. Many instances of this latter kind occurred 

 in 1912 where farmers plowed up in spring heavily infested wheat 

 because of winter-killing or injury by the Hessian fly, planting corn 

 at once on the same ground. The chinch-bugs already in the field 

 infested the corn as soon as it came up, and laid their eggs there for 

 the first new generation of the year ; and these presently appeared in 

 numbers to destroy the corn completely when it was only a few inches 

 high. A general spraying of this young corn with Black Leaf 40, 14 

 ounce to the gallon, saved the crop in many fields at a comparatively 

 trifling expense. 



Other corn-fields became infested in the same way by reason of a 

 cool spring which produced a heavy growth of wild grasses in the 

 old corn-fields before they were plowed. The chinch-bugs laid their 

 eggs on these grasses in immense numbers, and when the fields were 

 plowed and planted to corn the young bugs destroyed the corn plants 

 except where effective spraying was done. 



Insecticide Sprays in Wheat Fields. — In the latter half of April, 

 1912, a number of field experiments were made with sprays applied to 

 chinch-bugs in wheat fields with a view to learning whether it might 

 be feasible and profitable to destroy the bugs at that season of the year 

 after they had gone into the wheat, particularly where, as is often the 

 case, certain patches of the wheat were much more heavily infested 

 than the remainder. To secure precise results chinch-bugs were taken 

 from their winter shelter, usually bunch-grass, and placed in plots of 

 wheat a yard square surrounded by a road-oil line to prevent the 

 escape of the insects. The wheat was three or four inches high at the 

 time. 



In each of three such experiments, twenty bugs, taken from the 

 plot after it had been thoroly sprayed, were placed in a cardboard 

 box, and left there for twenty-four hours. In one where a sixth of an 

 ounce of Black Leaf 40 was used to the gallon of water, eight of the 

 twenty in the box were dead after twenty-four hours, and six others 

 were so affected that they were not able to crawl. They doubtless died 

 later from the effects of the treatment. In still another experiment, 

 where one fourth of an ounce. of the tobacco extract was used, all of 

 the twenty bugs were dead after twenty-four hours except two which 

 could still make slight movements of the legs; and in a third experi- 

 ment of the same character, three of the twenty were able to crawl and 



