28 Syrphidae. 



which the author has laid upon them; the differences in the hairiness 

 of the squamulæ, their fringes, the presence or absence of a stigma- 

 tical cross-vein, the corrugation of the wing-membrane etc. seem to 

 be characters which are not, at all events far from always, bound to 

 systematic groups, and the characters are also very graduated from 

 being distinctly present to quite wanting. 



The venation of the wings offers, I think, no difficulty in under- 

 standing; the lower marginal cross-vein is, I think, to be interpreted 

 as a branch from the discai vein (compare f. inst. the wing of Bom- 

 hylius); the vena spuria is less easily miderstood; it is convex; Redten- 

 bacher considers it as a branch from the radial system (the vein III); 

 Brauer is of a similar opinion considering its basal part to the inter- 

 ruption as being the real stem of the cubital vein, and its continua- 

 tion as a branch from this vein. (Perhaps it might be a rudiment of 

 vein V, the discai vein then only formed of vein VI). Brauer thinks 

 that the cross-vein, which is generally considered as the medial cross- 

 vein, is not this vein, but a branch from the cubital vein; as the place 

 for the real medial cross-vein he considers the thickening or interrup- 

 tion on the vena spuria, referring to Microdon; Girschner says, that 

 his observations have not confirmed this view ; Brauer's consideration 

 is interesting, but it is at present not possible to say anything cer- 

 tain about this question ; if upon the whole the medial cross-vein in 

 the Muscids is always the same vein I think however our medial cross- 

 vein in the Syrphids may be in reality this vein. 



The developmental stages of the Syrphids are rather well 

 known and of most genera they have been more or less studied. The 

 larvæ are rather various in appearance, and their biology is at the 

 same time very different. The larvæ of most genera of the subfamily 

 Syrphinae are aphidiphagous and live free on the piants among Aphides 

 (or Coccids); this holds good for Paragus, Triglt/phus, Pipizella, 

 Cnemodon, Pipiza, Melanostoma, Lasiophthicus, Syrphiis, Sphaerophoria 

 and Baccha. The larvæ of these genera are more or less leech-like, 

 generally attenuated towards the head-end and here most narrow, and 

 they have distinct mouth hooks and a short posterior spiracular pro- 

 cess; the pupa is more or less drop-like, and has no anterior spira- 

 cular tubes ; the larva of Melanostoma has been observed also to take 

 other prey than Aphides, f. inst. Diptera and Lasiophthicus .pyrastri 

 is recorded to have been bred from a pupa of a Plusia; if this latter 

 is not erroneous the larva must have gone into the Plusia-\arwa in so 

 late a stage that this latter has reached to pupate, and then the Syrphid 

 larva has eaten it out and pupated in it, and this may well be pro- 

 bable. The larva of Xanthandrus, which genus is so closely allied to 



