298 



Frit Fly: 



[august, 



are quite spoiled ; the land is very clean and in good heart ; 

 it is about five years since the maggot first appeared on my 

 farm and then quite destroyed a piece of nine acres ; it is 

 good medium land and up till the last few years has been noted 

 for its good oats." In the various samples sent either maggots 

 or puparia of the Frit Fly were found. 



Symptoms and Result of infestation. — (i) Pale spots may show 

 on the upper parts of leaves still green, the result of the gnawing 

 of the tissue by the larva before it proceeded downwards and 

 inwards ; (2) a browning or reddening of the leaves ; and (3) a 

 stunted growth and failure of the plants. The plant may not 

 be hopelessly destroyed as there may be a tendency to tiller ; 

 the new shoots, however, are often twisted and swollen and 

 simulate the appearance of eel- worm infestation. I found 

 this to be quite marked in some of the material examined. 



Where the grains, are attacked they are hollow, shrunken 

 and shrivelled. 



Description and Life History of Insect. 



Fly. — The adult fly measures less than -J- in. in length, the 

 body is bright shining black, and the legs are also black, save 

 the feet which are yellow or brown-yellow. The wings are 

 delicate and transparent, with the fore-edge brown. In A the 

 fields, the fly has a characteristic skipping movement. 



Larva. — The maggot measures -J- in. in length and is round, 

 fleshy, and legless. At the front end are two curved mouth- 

 hooks, and at the blunter hind end, on examination with a lens, 

 there may be seen two projecting spiracles. Under a good 

 magnification branched respiratory processes will be found at 

 each side of the head. 



Puparium. — The maggot pupates under cover of its last 

 moulted skin ; the resulting puparium or pupa-case is round 

 and red-brown with the spiracular processes at the hind end 

 well marked. 



Life History — Typically three generations are possible in the 

 year. The flies of the first generation issue in April and the 

 beginning of May, and proceed to lay their eggs on the young 

 oat plants. The eggs are laid on the leaves. The maggots on 

 hatching pass to the lower part of the plant, behind the leaf 

 sheaths and right into the heart of the plant. The full grown 



