REPORT OF THE DIRECTOR I919 21 



Several less-known corn insects were also brought to the attention of 

 the Entomologist. 



The material received during the past season has made possible a 

 more accurate appraisal of the economic status of these different 

 forms and in order to facilitate their recognition a popular key giv- 

 ing the more conspicuous characters was prepared and generally 

 distributed as a special folder. Additional details regarding the 

 work of the different species may be found in the Entomologist'^ 

 report. 



Small grain pests. Studies of the wheat midge, Thecodip- 

 losis mosellana Gehin., begun in 1919, were continued the 

 past season and much additional information secured concerning the 

 economic status of the pest. It was found to be generally present 

 in the rye fields of the eastern part of the State and in wheat fields 

 in tlie western area. It was particularly abundant in portions of 

 Genesee, Monroe, Niagara and Wayne counties, the indicated reduc- 

 tion ranging from 17 to 27 per cent with very little crop injury 

 from wheat scab or loose smut. The data show close correlation 

 between the abundance of maggots and the number of shrunken or 

 blasted grains of wheat and rye. The evidence at hand indicates a 

 presumably much greater loss from w^heat midge infestation than has 

 hitherto been suspected. A detailed discussion of the data is given 

 in the Entomologist's report. The collation of similar data for 

 1920 is in progress. 



The Hessian fly, Phytophaga destructor Say, is 

 one of the most destructive and best known wheat pests. Through 

 the courtesy of Prof. C. R. Crosby of Cornell University and W. R. 

 McConnell of the United States Bureau of Entomology, the Ento- 

 mologist has been able to include in his report summarized data 

 concerning the abundance of this insect in the State for the years 

 191 7 to 1919 inclusive. It will be seen by reference to the discus- 

 sion in the body of the report that there has been an increase in the 

 average infestation from 2.6 per cent in 1918 to 7.44 per cent in 

 191 9, the most marked increases occurring in Genesee, Monroe and 

 Wayne counties. These data are of value since they indicate tend- 

 encies in different parts of the State and can be used advantageously 

 in designating areas where stricter adherence to precautionary 

 measures is advisable. 



Wheat joint worms, Isosoma tritici Fitch and I. v a g i - 

 n i c o 1 u m Doane, occur throughout the State and as in the case 

 of the Hessian fly, data have been included concerning the abun- 

 dance of these two insects for the years 1918 and 1919. Reference 



