F. R. Petherbridge 3 



In a sample of spring wheat from Chaul End, near Luton, sown the 

 third week in April, 1916, three larvae and two empty pupa-cases of 

 the "frit fly" were found on October 3rd. (Other larvae very similar to 

 those of "frit fly" but not yet identified were also found.) This crop 

 was also badly attacked by the "Hessian Fly" Cedidomi/ia {Mayetiola) 

 destructor and a number of young tillers were present as is usual in 

 late-sown spring wheat. 



Hitherto three broods of the "frit fly" have been recognised. 



Brood 1 appears in April and May and lay their eggs on spring corn. 



Brood 2 appears in July and lay their eggs on the ears of oats or 

 barley or on the shoots of cereals and grasses. 



Brood 3 appears in August and September and lay their eggs on the 

 shoots of grasses or early-sown winter corn. 



Without further knowledge of the life history it is difficult to 

 account for the above attacks on winter wheat. 



Among the possibilities which would account for these late attacks 

 of winter wheat are the following: 



( 1 ) The third brood of flies may hatch out over a very long period 

 and the last ones lay their eggs on winter wheat. 



(2) Some of the third brood of flies may be capable of living until 

 December before laying their eggs. 



(3) The larvae of the third brood of flies may under certain con- 

 ditions give rise to a fourth. brood of flies which lay their eggs on winter 

 wheat. 



(4) In a letter Fryer suggests that "The third brood of flies may 

 migrate from the plants on which they hatched to the wheat which is 

 sown after the former host plants are ploughed in." 



Cases 1, 2 and 3 seem rather improbable as it would necessitate the 

 emergence of the fly in cold weather of which at present there is no 

 record. 



Case 4 seems more probable as several observers have found "frit 

 fly" larvae in the shoots of grasses and it is quite possible that migration 

 takes place from these plants to the wheat. This would also account 

 for the absence of the adult fly in the winter months. 



It will be seen from the above that more knowledge of the life history 

 of the "frit fly" is needed in order to find out the most efficient means 

 of reducing attacks on winter wheat. We know that early-sown spring 

 corn in a good seed bed usually escapes attack, but as the fly can lay 

 its eggs on grasses there is always the danger that our winter wheat will 

 be attacked even if we sow our spring corn early. 



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