Norman Cunlipfe 119 



A, B and F (1920) were drilled with the variety "Excelsior" on 

 Mar. 4th to 10th. 



In 1919, therefore, crop A presented host plants more suitable for 

 oviposition at the time when the flies were abundant, and this crop was 

 most heavily attacked. In 1920 when the seeds were drilled in at about 

 the same times, the attack was more severe on the land which had been 

 heavily infested the previous year, even thoufi;h there was no apparent 

 difference in the condition of the crops. 



B. HOST PLANTS AMONG WILD AND PASTURE GRASSES. 



It has been assumed that grasses are the host plants of the frit-fly 

 during the winter, because frit-like larvae have been discovered in 

 various grasses at this time of year. 



Ormerod(2i) records, from Continental literature, that "the larvae 

 are found in meadow grasses in summer." The normal utihsation of 

 grasses, as alternative hosts, was evidently not reahsed. In the previous 

 year it was recommended that oats should be left out of the rotation for 

 a while, in badly infested districts, " as the surest method of all to prevent 

 a continuance of attack." Ritzema Bos (23) records that the larvae live, 

 according to the time of year, in wild or pasture grasses, and Carpenter (6) 

 evidently quotes from similar records. 



Edmunds (12) states that he found the larvae in rye grass and also in 

 Avena flavescens and Arrhenatherum avenaceum, but he does not appear 

 to have bred them through to the adult stage, therefore he may have 

 been dealing with another species of Oscinella. 



Baranov (3) points out that the larvae hibernate in wild grasses (with- 

 out mentioning species), and also that the spring generation oviposits 

 on PJileum pratense, Alopecurus jpratensis, Lolium perenne, Triticum 

 cristatum, Festuca pratensis, Avena flavescens and Poa pratensis. 



Criddle (9), referring to 0. coxendix Fitch, reports, from Manitoba, a 

 severe infestation of cereals on grasslands ploughed in late autumn or 

 spring. But on permanent pastures in England, Cameron (4, 5) and 

 Morris (19) did not find frit-fly. Schjziyen (24) noted that the first genera- 

 tion deposited eggs on the leaves of young plants of quick grass and 

 timothy grass, Aldrich(i) in N. America bred flies from larvae which 

 had wintered in Phleufn pratense and Festuca elatior. 



Roebuck (1921)^ records the emergence of flies from Arrhenatherum 

 in the first week of May. The possibiUty of the fly breeding in such 

 common alternative hosts as wild and pasture grasses has therefore 



1 Ann. App. Biol vu, pp. 178-182. 



