105 



PRELIMINARY OBSERVATIONS ON THE HABITS 

 OF OSCINELLA FRIT, LINN.^ 



By NORMAN CUNLIFFE, M.A. (Cantab.), 



Christopher Welch Lecturer in Economic Zoology, 

 University of Oxford. 



(With 1 Text-figure and 2 Charts.) 

 CONTENTS. 



PAGE 



Introductory remarks ....... 105 



A. Prevalence of the imago in the field .... 106 



B. Host plants among wild and pasture grasses . .119 



C. Appendix : — ........ 123 



(1) The longevity of the imago in captivity . . 123 



(2) The value of ploughiaig as a repressive measure 125 



(3) The effect of manurial treatment . . . 129 



(4) Parasites ........ 132 



Summary 133 



INTRODUCTORY REMARKS. 



In his summary of our knowledge of the frit-fly, Collin (8) indicates that 

 elucidation of the bionomics of the fly in England is very necessary. 

 Most of the data published in recent years are Russian in origin, and 

 probably not applicable to this country. 



It was considered advisable to ascertain the relationship between the 

 fly and its environment, therefore the following observations were made 

 in 1919-20 with the view of obtaining evidence as to (a) the prevalence 

 of the fly in the field in the dift'erent seasons, and (6) the host plaats 

 additional or alternative to cereals. 



Observations on prevalence in the field must be obtained in different 

 locaHties, over several years and correlated with meteorological con- 

 ditions, for the periods of maximum prevalence to be fixed within the 

 limits induced by seasonal variations. The fixation of these periods will 

 be of importance if control through partial immunity is sought. 



' A grant in aid of publication has been received for this communication. 



