AA^ ATOMY OF THE GOUT-FLY OF BARLEY. 819 



Chlorojnsca glabra Meig. 



This fly was bred out in considerable numbers from various 

 grasses and has iilso been found infesting Winter Wheat and 

 J-jarley. It was originally intended to describe here the larval 

 fox-ni. The larva is, however, so extremely similar to that of 

 Oscinis frit that it has been decided to defer the description of the 

 C/doropisca until a detailed comparison of these two larva; can be 

 made. The only differences so far observed are the somewhat 

 larger size of the GJiloropisca larva and its rather more yellow 

 colour ; such dilTerences are obviously unsatisfactory. 



The chief winter host of Chloropisca is Lolium 'jjerenne. 



Winter Host-Plants of Chlorops XuhNiorcs, IIehomyza 



KlGUIVENTiaS, AND BaJ.IOPTEHA COMniNATA. 



After a considerable avnount of purely qualitative grass 

 examination had been done, an attempt was made to reduce the 

 Avork to a quantitntive basis by bringing in samples of the various 

 grasses, examining each shoot in the laboratory, and linding a 

 percentage figure of infestation. The figures were, however, 

 found to vai-y very greatly in samples of the grasses taken from 

 difterent localities and are not, J. think, worth giving. I consider 

 that to obtiiin a reliable infestation figure for a grass in this way, 

 at least 20,000 shoots would lia,ve to be counted, ta.ken in samples 

 of about 1000 shoots from ditlerent localities. Tliis is obviously 

 impossible Avhen one is examining a considerable number of 

 dilierent grasses. 



Chlorojjs tmiiiojnis has only been found in Agrojiyrum rej^ens 

 .among the wild grasses examined. Meromyxa nigriventris occurs 

 in A. 7-epens, Festuca ovina, and Alopecnrus pratertsis; Balioptera 

 comhinata occurs in A. repens, Festuca elatior, Lolium 2:>erenne, 

 IIolcus lanatus, and Agrostis alba. The following grasses have 

 also been examined but do not appear to function as winter hosts 

 for any of the above three species of flies: — Lolium italicum, 

 Pea pratensis, P. irivialis, P. annua, Agrostis vulgaris, Alopecurus 

 agrestis, Arrhenatheruvi avenaceum, Anthoxanthuvi odoiritum, 

 Arena ptubescans^ Gj/nosurus cristaius, and Dactylis glomerala. 



Winter Barley and Wheat a.re also attacked b}^ all three 

 species ; the conditions under which thej' are att.icked by Chlorops 

 will be dea.lt with in detail in a later paper. The effect on the 

 host of either Meromyza or- Balioptera, is very similar to that of 

 Frit Fly. The larvse live in the base of tin* shoot and destroy 

 tlie growing point, causing also the yellowing and death of the 

 central ]ea,vos by destroying their basal regioxia. Winter is passed 

 in the larval state. In spring the larva turns round in the grass 

 shoot until its head is directed upwards, ascends a short distance 

 up the siioot, and then pupates. . . 



