108 Observations on the Habits q/Oscinella frit 



made on alternate days. To avoid errors in identification^ the frit material 

 was separated under a binocular microscope. 



Data obtained by Sweeping. 

 The actual figures obtained as a result of sweeping are set out in 

 Tables I and II respectively, as they record the presence of the fly in the 

 field throughout the year except for the winter period October 20th to 

 April 27th, and it is very probable that more diligent search would 

 shorten this period by a week or two. 



Table I (1919). 



In "Remarks" column, D = sun obscured. 



S =sun not obscured. 

 Number = velocity of wind in miles per hour. 



No. of flies collected 



No. of flies collected 



After Oct. 19th, no captures in field. 

 Sweepings on B and C were discontinued after August 5th as the figures obtained up to that date 

 were confirmatory to those shown under A. 



The abundance of the flies on July 17th and August 20th, after rainy periods, should be noted. 



1 Mr J. E. Collin has informed me [in lift.) that he is convinced 0. frit is the only species 

 attacking oats in England. 



Only occasionally was O. pusilla Meig. observed in the material collected (which in- 

 cluded approximately 12,000 specimens of the frit-fly) and then never in large numbers, 

 nor was this species ever reared from puparia collected from oats in the field. On the other 

 hand 0. pusilla was bred from barley grains, collected at Garsington, Oxon., the flies 

 emerging on 17. 8. 20. Mr Collin, in confirming the identification, stated that, as far as he 

 was aware, this is the first record of this species attacking cereals in England. Again, this 

 species was bred from field specimens of Hordeum murlnum, two flies emerging on 13. 10. 20. 



