j 907.] Frit Fly. 299 



maggot pupates in the plant, and by the month of July the next 

 generation or brood of flies begins to come away. From my 

 own specimens I have bred out the flies by the 5th July, 

 but this season, at least in the open, the brood has probably 

 been a little later. If, from any cause whatever, the oat still 

 produces new young shoots the flies may lay on these, but the 

 flies of this July brood lay their eggs characteristically on 

 pasture and wild grasses or, if the stage of the plant suit, in 

 the ears of oat (and barley) where the grains are young. The 

 maggots of this brood then are harmful both to vegetative 

 parts and to grain. Infestation in the ears may not show 

 itself externally, the grains being under cover of the glumes, 

 but the result appears at the harvest in the shape of light 

 samples and of gnawed shrivelled grains. This attack on the 

 ears is more characteristic and severe in the northern counties 

 than in the south, as the age and condition of the ear render 

 it suitable for the egg-laying of the brood that developed itself 

 in young oat plants. 



By August and September the third brood of flies is ready. 

 The flies of this brood may on occasion be found in swarms 

 in places where infected grain has been stored, or in neighbouring 

 places. The flies of this third brood lay their eggs on such 

 grasses as are in suitable condition. The maggots feed and 

 pupate in due course, and from the puparia the flies, whose 

 egg-laying in the young oat begin the cycle for the year, issue 

 in the following April and May, 



Treatment. — 1. The foregoing life history will have made clear 

 the importance of a correct sowing period. The oats should be 

 put in as early as possible so that the plants may have made 

 some progress before the issue 'of the April and May brood 

 of flies. The flies choose for their egg-laying young tender 

 parts, hence grown plants are made use of less willingly, and 

 even if they are infested, they suffer less. 



The wisdom of early sowing in dealing with the Frit Fly 

 has received repeated confirmation. Miss Ormerod quotes 

 two cases : — " All early spring fields seem to have escaped^ 

 while in some others, sown late, 90 per cent, of the crop is 

 gone." Again, " One field of oats sown on 29th March 

 enjoyed almost complete immunity; in another field sown on 

 29th April over 70 per cent, of the first stems were destroyed." 



