Norman Cunliffe 167 



Previous experiments have shown that O.frit may, during the winter 

 period, breed on Alopecurus niyosuroides, Lolium italicum, L. perenne, 

 Hordeum pratense and Arrhenatlierum. avenaceum,. In addition to these 

 therefore, Holcus lanatus, Bromus sterilis, Daetylus glomeratus and 

 A. avenaceum var. bulbosum may be utilised during the winter. Miles (2) 

 states that, in the winter period, he obtained larvae of O.frit in Trisetum 

 {Avena)jlavescens, A. avenaceum., Agroslis stolonifera (a variety of ^. alha), 

 Holcus lanatus and L. perenne in the field, without indicating which host 

 was the most heavily infected. 



Grasses Utilised in Spring, Experiments IV and V. 



In the spring of 1921 small quantities of the tweuty-five grasses used 

 in the first three experiments were available, as well as a few roots of the 

 following species: Brachypodium sylvaticum, Avena pratensis, Festuca 

 rubra and Hordeum pratense. Single pots of each of these species were 

 placed under a large cage pn 4. iv. 21, infected with 149 flies from the 

 field on 18. v. 21 and separately caged in the middle of June. 



Reckoning from the date of infection the emergence of the next 

 generation of flies was as follows: Agrostis alba, 2 flies after 62 days; 

 A. avenaceum var. bulbosum, 2 and 1 flies after 42 and 59 days; Hordeum 

 murinum, 12, 7 and 1 flies after 55, 59 and 62 days respectively, while 

 in the same periods L. italicum, gave 1, 2 and 1 flies only; Poa trivialis, 

 4 flies after 55 days^. Thus, O.frit may exist on Agrostis alba, A. avena- 

 ceum, var. bidbosmn, Hordeum, murinum and Poa trivialis during the 

 spring period as well as in A. avenaceum, Festuca pratensis, L. italicum, 

 L. perenne and Poa annua, as shown by previous experiment. 



A similar experiment conducted in July gave negative results, a 

 period of high temperature occurring during this month, causing the 

 premature death of the parent flies. 



Experiment V. In the spring of 1921 the cereals, oats, wheat, rye, barley 

 and maize together with the grass Lolium italicum were grouped in the 

 same way as the grasses in the first experiment, five pots of each species 

 being used to ascertain whether the fly in captivity showed any decided 

 preference for oats. The cage was infected on 18. v. 21 with 56 flies from 

 the field and the pots separately caged in the middle of June. The 

 emergence of flies was small, wheat, rye, barley and maize yielding none, 

 L. italicum 1 and 4 flies after 50 and 59 days, oats, 1, 1, 1, 4 and 3 flies 

 after 47, 50, 59, 67 and 73 days respectively. 



^ A pot of Semle cereale included in the group was comparatively heavily infected, 

 5, 1 and 1 flies emerging after 55, 59 and 73 days respectively. 



