Brachyopa. 387 



corrugations are at the margins densely beset with small spinules; the 

 thoracai segments have some spines; on each of the abdominal seg- 

 ments is a transverse row of six spines which are bi- or trifid or still 

 more divided and with the apices curved and spread ; these spines are 

 placed on the anterior of the two corrugations but the two lateral 

 spines on each side are placed more backwards than the two middle 

 ones so that the arrangement is in reality the same as in other Syrphid 

 larvæ; likewise there are at the sides of the segments three spines, 

 one upper and two lower, one behind the other; these side-spines are 

 larger and generally four-rayed, between them there are small, simple 

 spines; on the last four segments the side-spines are larger, flattened 

 and with a number of branches on their sides. The ventral segments 

 are chagreened and with small spines towards the sides, among which 

 one bifid. The last segment has in the middle of the hind margin a 

 reddish, cylindrical but somewhat flattened spiracular process, directed 

 straight backwards; it is about 1 mm long. The larva is brown, of 

 a length of 10 — 11 mm. The pupa is quite similar to the larva and 

 of the same colour, only it is a little more arched above, the side 

 margins more sharp and the anterior segments declining more down- 

 wards ; at the anterior margin of the first abdominal segment are two 

 yellow or brownish, short spiracular tubes, not reaching 0,5 mm in 

 length; they are somewhat distant and a little diverging. The length 

 of the pupa is 8—9 mm. 



It will be seen that my description is in the main respects agreeing 

 with the one given by Leon Dufour, but in the details there are 

 several differences, as in the shape and position of the spines etc. ; 

 Leon Dufour's description and figures must be considered as rather 

 diagrammatical ; the author could not find the anterior spiracles, but 

 this is no wonder for they are detected only with difficulty among the 

 spinules. It is curious that he says that the small spinules at the 

 margins of the corrugations are present only in the pupa, as I have 

 found them even as distinct in the larva. 



The habits of the larva are, according to the above, well known; 

 they live in exsuding sap on ulcerative stems and stubs of various 

 trees as Aesculus, Ulmus, Populus and Fagus. The imagines are also 

 found on such piaces. Very often, but not exclusively, the larvæ are 

 found in stems attacked by Cossus. The larva feeds on the sap or 

 perhaps on microorganisms in it, and accordingly it has no mouth 

 hooks. The long posterior spiracular process is not pro- and retractile. 

 The pupæ are found on the same piaces as the larvæ. According 

 both to Leon Dufour's and to my observations the larva evidently 

 hibernates, and a year is used to the development, the eggs being 



25* 



