182 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 12 



examine the plot and to select typical square yards, thus if one-fifth 

 of the plot has a thin stand and the other four-fifths is heavy, we 

 should select one square yard from the thin and four from the thicker 

 area. One must, of course, be thoroughly unbiased in making his 

 selections. Having selected an area, a yard stick is placed along one 

 row. Having cut this row, the corresponding yard on the next row 

 is cut and so on until five rows or approximately one square yard is 

 taken. (PI. 7, fig. 1.) Five such areas are cut from each plot, 

 cured, placed in bags and shipped to a central point for threshing. 

 The data taken includes not only weight of straw and grain, but also 

 the grain is tested and its quality recorded, for we find the Hessian 

 fly is responsible for damaging the quality as well as the yield of wheat. 

 As stated, we have no proof that one means of obtaining yields is 

 better than another and indeed it appears that the practice just de- 

 scribed does give us records above the actual yields, but we have every 

 reason to believe, and much proof to show that the method we have 

 used is comparable, which after all is the most important item. 



Method of Estimating Injury 



Estimates of injury by this or that insect are frequent in entomologi- 

 cal literature, but seldom if ever have the methods used in estimating 

 the injury been noted. No rules can be given to fit all cases. Cer- 

 tain methods which we have used are here offered, with the object of 

 securing expressions of opinion and additional ideas from the members 

 of this association. 



Estimating the injury where acreages are killed outright is com- 

 paratively simple, but where injury is inconspicuous the difficulties 

 are evident. In the former category we may include damage by white 

 grubs, army worms, grasshoppers and chinch bugs when attacking 

 corn, while in the latter group would be included injuries by scale 

 insects, corn root aphis, Hessian fly, chinch bug in wheat, and joint 

 worm. 



In some cases where the insect damage is restricted to a definite 

 area, it is possible to obtain an accurate estimate of injury by compar- 

 ing yields of this area with a similar uninfested area in previous years 

 as well as the year of injury, consideration being given to the chmatic 

 conditions in the two areas. Where the injury is widespread we know 

 of no other method than comparing the yields during the season of 

 insect injury with previous seasons yields, due weight being given 

 insect injuries in previous years, and comparableness of chmatic con- 

 ditions and acreage. In estimating injuries where the damage is 

 evident, the percentage of injury can be corroborated to a certain 

 extent by a general survey and careful estimate of individual fields, 



