1906.] 15 



as regards the fly, and I am glad to be able now to supplement it with further 

 observations, which go to show that I his is the usual, possibly the only, manner of 

 life o{ Xanthandrus cointus, and justify my publishing a further note on the species, 

 for the benefit of students rather of Diptera than of Lepidoptera. 



In Sicily this spring I looked for and found larvae of H. hyerana, which were 

 by no means rare, but here, instead of being gregarious, they were quite solitary, 

 a fact to be dealt with in further notes on H. hyerana. As regards X. comtus, 

 however, the result was that I found no trace of the fly in connection with it. I 

 attributed its absence to the fly being possibly absent from the Sicilian fauna, but I 

 also thought that possibly the isolation of the individual larvse, rendered them here 

 an unsuitable prey for this parasite. 



I was lucky enough to meet with proof that the latter was almost certainly the 

 reason that H. hyerana is here free from its attacks. 



Having collected some larvae of AcrocUta consequana, I found some time 

 after I had had them at home, that larvae of X. cotntus were present with them, 

 and I bred specimens. 



Now it so happens that A. consequana in the Riviera, is a solitary larva, and 

 there I never met with X. comlus with it. But in Sicily it is gregarious, gre- 

 garious in this sense, that though each larva occupies its own special bud or shoot, a 

 bush of Evphorbia in which it occurs, usually has a large number of larvae on it, up 

 to a good many dozen, the Euphorbia bushes it affects being large and thick, and 

 from three to five or more feet high, quite different from the more herbaceous 

 growth of the species of Euphorbia on which one finds it in the Riviera. 



X. comtus, therefore, occurs in Sicily, and we may, I think, assume that it 

 would attack H. hyerana, if that species afforded a sufficient number of larvae on 

 one plant. Of course, it is possible that it does attack S. hyerana and other soli- 

 tary larvae here, but it is inevitable that when it does so the larvae would perish 

 when it had destroyed its solitary prey and could find no others. 



These flies emerged from April 15th onwards, much the same dates as those 

 bred from H. hyerana at Hyeres. 



It so happened, however, that I again met with the larva of X. comtus this 

 year. On August 8th, in the valley below Le Laularet, towards Monetier, at 

 about 5500 ft., I found two or three bushes of Bhamnus pmnilus, of which every 

 shoot, nearly every leaf, contained a half-grown Tortrix larva, probably of Ancylis 

 A derasana. A day or two after I brought some of these home, there appeared 

 amongst them larvae of X. comtus, of which I bred two some weeks later.* Here 

 again the prey of the fly was a quasi-gregarious Tortrix larva. So abundant were 

 these larvae, that I concluded they were full fed or nearly so, and of some small 

 species ; for the simple reason that there would be no food for them if they had to 

 grow to any size, however, they grew very much larger, and it is certain that if the 

 fly allowed any larvae to escape it, then it benefited these survivors, which must 

 otherwise have perished of starvation. 



There is a possibility of mistake in piecing together portions of life-histories 

 from the Mediterranean coast and 6000 ft. elevation in the Alps, but it is clear that 

 X. comtus feeds especially on the larvae of Tortrices when there are many on a plant. 

 It seems also most likely that there are several broods during the season. By 

 collecting Tortrix larvae of similar habits in places where X com^w* occurs, it ought 



