Feb. 2. 1920 European Frit Fly in North America 465 



grass lawn at Elk Point, S. Dak., by C. N. Ainslie. This was on Sep- 

 tember 7. 



This was exceeded five times in 191 6, when the highest record was 486 

 flies in 200 sweeps with a i3X-inch net on bluegrass lawn at the Central 

 Experiment Farms, Ottawa, Canada, by Mr. Germain Beaulieu, on 

 August 17. Both of these records indicate a great concentration of the 

 flies upon this food plant in late summer. However, an earlier record 

 stood second in 1916, when Dr. C. F. Adams swept 401 flies in 200 sweeps 

 of a 12-inch net at Atherton, Mo., on bluegrass lawn, on May 17. 



INFESTATION OF WHEAT 



Almost all the infestation observed by the writer has been upon wheat. 

 Eggs are laid on fall wheat soon after it comes up, and the larvae winter 

 in the stems. Wheat was sown at weekly intervals from September 12 

 to October 17, and in November it was noted that the infestation was 

 great in the earliest sowing and decreased regularly to the latest one or 

 two sowings, in which none could be seen. In the spring the wheat is 

 attacked by the first summer brood. Spring wheat is not a farm crop 

 at La Fayette, but experimental sowings, especially the later ones, were 

 heavily attacked. 



A very characteristic symptom of infestation in young shoots of all 

 kinds is the dying of the central leaf while the others around it remain 

 green. The observer readily notices this when once his attention is 

 directed to it. In the cooler and moister periods of the year, however, 

 the insect may be abundant and yet only a few of the plants show this 

 symptom. Since the larva does not usually cut the central leaf entirely 

 off, in periods of low transpiration the leaf will still keep green for some 

 time, whereas the same injury in hotter and dryer weather would kill the 

 leaf at once. So the damage may be greater than it appears and can be 

 calculated for the cool part of the year only by placing a known number 

 of plants in a cage and counting the flies that emerge, every one of which 

 may be considered to have destroyed a shoot. 



At a meeting of Russian economic entomologists in Kiev in 191 3, Mr. 

 N. V. Kurdjumov (r) advanced the theory that the pruning off of some of 

 the shoots of summer grain by Oscinis frit may do it good rather than harm. 

 But the same author {12) in the same year mentions the insect as inflicting 

 particularly severe injury upon spring grain. Since several other Rus- 

 sian entomologists have reported it to be doing serious injury, it is 

 likely that its possibly useful character was mentioned in a qualified way. 



Although in garden-sown wheat infestation occurred in a considerable 

 percentage of the stems, the writer was never able to find in fields of 

 winter wheat any appreciable infestation in late fall or early spring, 

 such as was reported by Garman. For a while this was explained appar- 

 ently by the fact that at these seasons of the year the characteristic 



