A. Roebuck 179 



The larvae migrate in the spikelets as the food is exhausted and attack 

 very young flowers but the glumes and palea are left. 



The only insects I have found in or around these "blind" spikelets 

 have always been those which were apparently sheltering, or possiblv 

 attracted in the early season by these white patches in an otherwise 

 uniform green background. 



Continuing observations on this problem the following facts were 

 obtained during the summer of 1919 which point to a direct connection 

 between the "blindness" and frit fly. 



Observations. 



The Blindness, Deafness or White Ear referred to is most noticeable 

 comparatively early in the season when the oat panicles are unfurling 

 from the sheath and are a good deep green colour. The "blind " spikelets 

 then stand out clearly almost white. They consist almost always of the 

 two flowerless glumes, often with branches of the rachis twisted and 

 blanched. 



In a field of Abundance oats very severely attacked by frit fly the 

 panicles began to unfurl about the 20th June and large numbers of 

 "blind"' spikelets were noticed. 



Examination of several ears still enclosed in the swollen sheath on 

 June 24th, revealed the presence of a larva of frit fly in a number of these, 

 feeding amongst the folded flowers. Subsequent examination of unfurled 

 panicles made frequently until the end of July showed in many cases 

 two or even three larvae. The intensity of the attack causins; irregular 

 ripening through the production of more tillers, coupled with the fact 

 that plots were sown at different dates extending into May, enabled the 

 observations to be made over this extended period. The larvae were 

 found anywhere amongst the curled up mass of the panicle protected 

 from the outside by the enclosing leaf and destroying completely the 

 enclosed flowers, leaving the blanched flowerless glumes and curled 

 branches of the rachis. In the worst cases the whole panicles were 

 destroyed leaving only the central axis and branches which presented a 

 blanched and twisted appearance on unfurling. 



Further search on the same day, June 21th, in those cases where the 

 first spikelets of a panicle had emerged, revealed several pupae. The 

 pupa is fixed amongst the curled up mass, apparently anywhere — on the 

 outside of the spikelet, rarely inside it, on the rachis or more rarely on the 

 inside of the leaf sheathing the panicle. 



