Feb. 2s. 1918 Relation of Grain to Hessian-Fly Injury 52 1 



The relative number of flaxseeds in each variety was determined by 

 examining 50 consecutive plants of each row in each plot sown on Septem- 

 ber 15, and 25 consecutive plants of each row in each plot sown on 

 October I , making a total of 1 50 plants of each variety. All plants were 

 taken from the western end of the plots, or, in other words, adjacent 

 to those plants which were examined for eggs. The pertinent data for 

 each variety are given in Table I. 



That the Hessian fly is apparently able to discriminate between kinds 

 and varieties of grain is shown by these data. For example, the total 

 number of eggs per 100 plants in the early sown plots ranges from 40 for 

 Culberson winter oats to 5,600 for Turkey winter wheat No. 2407. The 

 proportion of plants on which eggs were laid varied from 20 per cent for 

 Culberson winter oats and Michigan winter barley to 100 per cent for 

 Tennessee winter barley and most of the varieties of wheat. 



The close agreement in determinations made at different times, and the 

 striking differences in the number of eggs laid on adjoining varieties indi- 

 cate that the difference can scarcely be attributed to experimental error. 

 Thus, Turkey winter wheat No. 2407, which showed the highest total num- 

 ber of eggs, also had the highest infestation on September 25, the second 

 highest on October 10, when the second determination was made, and was 

 among the highest on October 7, when the third determination was made. 

 On the other hand, Culberson Winter oats, Michigan Winter barley, and 

 einkom had the lowest total infestation and the lowest on each date. 



Row 12 (Polish wheat) had a total of 2,040 eggs per 100 plants, as 

 compared with 280 for row 13 (einkorn). Row 15 (spring emmer) had a 

 total of 660 eggs per 100 plants, as compared with 1,740 for row 16 

 (Black Winter emmer). 



On the whole, the Hessian fly appears to have shown a preference for 

 common wheat, as compared with barley, oats, einkorn, spring emmer, 

 spelt, and durum wheat. Black Winter emmer. Poulard wheat, and 

 Polish wheat were as heavily infested with eggs as many of the common 

 wheats. Rye showed a very heavy infestation, the total number of eggs 

 per 100 plants being 2,500, which is well above the average for all grains 

 included in the test. 



Varieties of the hard winter wheat class were more generally infested 

 than soft winter wheat varieties. Thus, 27 varieties of hard winter 

 wheat averaged 2,737 ^ogs per 100 plants, as compared with an average 

 of 1,835 for 38 varieties of soft winter wheat. However, there are wide 

 variations in each class. For example. No, 2408 and Mealy, which are 

 soft, or semihard, varieties, were infested with 4,720 and 4,320 eggs, re- 

 spectively, per 100 plants, showing almost as high an infestation as the 

 most profusely infested varieties of hard wheat, and more than double 

 that of some varieties. On the other hand, certain varieties of hard 

 wheat, such as Defiance No. 2129, Red Winter No. 839, Improved Tur- 

 key No. 2382, and Pesterboden No. 205, had a lower infestation than the 

 average of the soft, or semihard, varieties. 



