364 Frit Fly (Oscinis Frit) in Winter Wheat 



Plot B Fed ofi by sheep. 



Ploughed on October 1st, 

 then harrowed, 

 and drilled on October 3rd. 

 Plot C Fed ofi by sheep. 



Ploughed on November 1st, 

 then harrowed, 

 and drilled on November 3rd. 

 The results observed were as follows : 



Plot A. Although I made several careful searches I did not find a 

 single plant attacked by frit fly. 



Plot B. Fairly bad attack of frit fly. About 10 per cent, of the plants 

 attacked. 



Plot C. This plot was damaged by birds, so that it was difficult to 

 estimate the amount of damage, but many frit larvae were found. 



This experiment was repeated in 1919-1920 with a view to deter- 

 mining when the frit fly larvae migrate from the rye grass into the wheat. 

 Before ploughing in the autumn the Italian rye grass was examined 

 and found to be very badly attacked by frit fly larvae, which were 

 feeding on the young shoots. The intensity of the attack was probably 

 increased by the ploughing up of over 90 per cent, of the rye grass in 

 summer and thus leaving a much smaller amount of grass in which the 

 flies could lay eggs. 



Plot A. Crop in 1919 — Italian rye grass and trefoil. 

 Ploughed July 25 th. 

 Wheat drilled October 30th. 

 Very few frit larvae found in wheat. A few also found in Italian 

 rye grass plants not ploughed under. A few plants attacked by wheat 

 bulb fly. 



Plot B. Crop in 1919 — Italian rye grass and trefoil. 

 Ploughed November 7th. 

 Drilled November 20th. 

 About 25 per cent, of the plants attacked by frit larvae. A few plants 

 attacked by wheat bulb fly. 



Plot C. Crop in 1919 — Rye and vetches. 

 Folded with sheep. 

 Wheat drilled in July, 1919. 

 A few frit fly larvae found. A few wheat bulb fly larvae attacking 

 wheat and couch (Agropyrum repens). 



