1)2 Slwrf SiiiiiitHirii of our Knotiicchje of the Frit-fii/ 



hav^e been Hi/leiiiyKi coardaia, the damage by tliis insect and by Oscinia 

 frit often being confused {vide Wahl, 1914 and Dafert and Kornauth, 

 1911). It has been noted that on a field of wlieat after Italian rye-grass 

 and clover, where it was ploughed in July, bastard fallowed, and drilled 

 on October 3rd, there was no frit attack ; while another part of the same 

 field where the grass and clover crop was fed ofi by sheep, ploughed on 

 October 1st and drilled on October 3rd, 10 per cent, of the wheat plants 

 were attacked (Petherbridge, November, 1917). On the Continent, in 

 addition to late sown spring crops on newly broken land, spring corn 

 planted next to winter rye is almost always attacked, the attack spread- 

 ing from the rye in parallel lines or concentric circles (Cohn. 1869). 



POSSIBILITY OF INFECTION FROIVE INFESTED SEEDS. 



Those larvae attacking the grain of oats in the panicles, often pupate 

 within the husk of the oat and remain in the corn after it is threshed; 

 the flies normally emerge during August and September and several 

 records of the occurrence of swarms on oats threshed early in August 

 have been noted {ride under " Imago ""). In order to account for infection 

 from the seed it would appear necessary for there to be either (1) deferred 

 emergence on the part of some of the flies from pupae in the grain, or 

 (2) oviposition on the corn by the females of the emerging flies, with the 

 larvae hatching out after the corn is planted. Neither of these supposi- 

 tions appears very probable, but attention has been called to this possible 

 source of infection by Miss Ormerod in 1889, by the author of an article 

 in the Journal of the Board of Agriculture for September, 1901, and by 

 Kulagin (1913) in Russia; while quite recently (1917) in England 

 observations have been made in districts where frit -fly is very prevalent 

 that when seed from districts where oats do not suffer to the same 

 extent from the fly has been used, the crops in some cases have not been 

 seriously attacked, and that where seed has been dressed with corvusine, 

 seedolin, or sulphate of copper, the crops have been fairly free from 

 attack (Hland. -Inly, 1917). Moreover, in an experiment in which seed 

 from a l)adly attacked field was sown under a fine mesh n\uslin frame 

 which seemed to be im))ervi()us to the flies, an examination of half 

 the plants at the end of .liinc brought to light two frit larvae (Roebuck, 

 Shropshire. 1917 in litl.). 



REMEDIES. 



Spring sowings should be as early as possible, and the early growth 

 stimulated in order that the young plants may be as forward as possible 

 at tilt' time of api)earanre of the first brood of flies, for then the small 



