proceedings: entomological society 277 



interpolation instrument, using one or more metal freezing points for 

 calibration. An outstanding discrepancy of 7 degrees in the values 

 obtained by different methods for the melting point of palladium makes 

 the adoption of uniform scale for temperatures above 1200 degrees a 

 difficult matter at present. 



Discussion: The paper was discussed by Messrs. White, Adams, 

 ToLMAN, and Tuckerman. 



The Society adjourned at 10.06. 



S. J. Mauchly, Recording Secretary. 



ENTOMOLOGICAL SOCIETY OF WASHINGTON 



322ND meeting 



The 322nd regular meeting of the Society was held in the auditorium 

 of the Cosmos Club on May i, 1919. Vice-President Walton was 

 in the chair and there were present sixteen members and one visitor. 



The regular program was as follows : 



A. B. Gahan: The black grain-stem- saw fly of Europe in the United 

 States. This paper dealt with Trachelus tabidus (Fab.), the establish- 

 ment of which in the United States has been recently discovered. This 

 insect may become a serious pest of small grains, especially wheat. 

 Some of the points discussed were distribution both in the United States 

 and in the Old World, character of injury, description of adult and larva, 

 and a comparison with related species, suggestions for control, and 

 bibliography. The illustrations consisted of drawings of the adult, 

 the larvae of this and two allied species of similar habit, and a map of 

 the distribution in the United States. 



In the discussion Mr. Walton stated that Mr. McConnell of the 

 Bureau of Entomology had discovered a parasite that killed as high as 

 30 per cent of the sawfly larvae. Dr. QuainTance remarked that this 

 appears to be one of the few cases in which the necessary means for 

 insect control conflict with good agricultural practice, the rotation of 

 clover and wheat being undoubtedly good agricultural practice and also 

 favoring reproduction of the insect. Mr. Walton took exception to 

 this, stating that forage experts claim that better clover can be grown 

 on plowed land; but planting on stubble is easier and cheaper. Mr. 

 ROHWER stated that sawflies are sluggish fliers and was of the opinion 

 that if in the rotation, fields to be planted to grain were far apart, the 

 infestation would be considerably reduced. Mr. Gahan thought that 

 the fact that the species is already widely distributed in both mountain 

 and plains regions indicates considerable ability to spread. Winds as 

 a means of spread being suggested, Mr. Rohwer stated it as his experi- 

 ence that sawflies seek shelter in high winds. He also stated that the 

 species is possibly more widely distributed than outlined by Mr. Gahan, 

 inasmuch as he has a larva from near Parkersburg, West Virginia, that 

 is probably this species. 



