Norman Cunliffe 123 



Actually there was no sign of a central gallery such as is drilled by the 

 frit larva, but only a small lateral cavity, low down on the stem, probably 

 due to the attack of the larva of a Tipula sp. 



Later in the season (8. 6. 20) Alopecurus myosuroides {— agrestis) on 

 plots A and B (Fig. 1) was found to be infested to the extent of 89 per 

 cent. (137 plants), the infestation of the oat crop at this time being only 

 70 per cent. The identification of flies bred from this grass was confirmed 

 by Mr J. E. Collin. 



Examination of the winter oats on plot C (Fig. 1) on 23. 3. 20 showed 

 that infection was very Hght. Nine samples, averaging 55 plants each, 

 were collected at random about every 3 feet and examined by dissection. 

 Only 0-7 per cent, of the plants contained frit-fly larvae and 0-6 per cent, 

 showed signs of boring without containing larvae. On 14. 6. 20, however, 

 larvae were very numerous in the young tillers. 



These oats followed a crop of winter oats in 1919. 



C. APPENDIX. 



Whilst making the investigations previously described, various notes^ 

 of economic interest were compiled and are presented under the following 

 headings : 



(1) The longevity of the imago in captivity, 



(2) The value of ploughing as a repressive measure. 



(3) The effect of manurial treatment. 



(4) Parasites. 



The Longevity of the Imago in Captivity. 



As there appear to be no records of the longevity of the adult flies 

 in England the following data is of interest. Observations were made on 

 flies kept at the same temperatures, with and without food and moisture, 

 in the spring and summer seasons. 



It may be pointed out that Continental records vary very considerably 

 (from 1 day to 5 months), but the environments doubtless varied also. 



Method. 



The flies were reared separately, in tubes, from puparia collected in 

 the field, either from oat stems or oat grains according to the season, 



^ To comply with the recent decision of the Publications Committee, this paper has 

 been curtailed considerably, notes on the action of the larvae on the host plant, on copula- 

 tion and oviposition and on the ratio of the sexes in the field having to be omitted. 



