Melanostoma. 229 



I have myself examined the pupa found sitting on stalks of Garduus 

 on 2^7, they developed on ^Vt and ^'Vt, and others from larvæ in 

 flood refuse, which latter developed in April and May. The empty 

 puparium is whitish, translucent, similar to that of Platychirus but 

 more tapering behind and more drop-like; the posterior spiracular 

 process is short as in Platychirus; I have not been able to decide 

 whether there are small anterior spiracular tubes as in Platychirus or 

 not. The pupa has a length of 6 mm. According to the above the 

 larva is carnivorous, either feeding specially on Aphides and only ex- 

 ceptionally on other prey, or perhaps upon the whole taking various 

 prey. According to Griinberg the larva hibernates, which would be 

 in accordance with the facts found by me in Platychirus, and the 

 above mentioned pupæ developing in April and May indicate the same, 

 but Girard found the imagines developing in September, and some of 

 my pupæ developed at the end of July; it seems thus, that the 

 hibernating of the larva is no fixed rule; probably there are more 

 than one brood in the year, or the development is upon the whole 

 somewhat irregular (which may be the case also with Platychirus), 

 and then it is most probable, that the larva (of one brood) hibernates 

 in a younger or older stage. 



The species of Melanostoma occur on similar localities as those 

 of Platychirus-, the genus is widely distributed and goes far towards 

 the north, one species (ambiguum) being found in Greenland. — Also 

 in this genus so-called hermaphroditic specimens occur; Villeneuve 

 mentions (Feuille des jeunes Nat. V, 42, 1912, 111) two females, one of 

 scalare and one of mellinum, both with a rather narrow frons; both 

 specimens were melanoid. 



Of the genus 8 species are known from the palæarctic region; 3 

 occur in Denmark. 



Tahle of Species. 



1. Abdomen in the male with greyish hoary spots, in the 

 female almost unspotted ; front femora in the male with a 



peculiar, curled hair near the tip 1. ambiguum. 



— Abdomen in both sexes with yellow spots; front femora 



of the male without any peculiar hair near the tip 2. 



2. Frons and epistoma not or almost not pruinose; arista 



almost bare ; abdomen not specially long 2. mellinum. 



— Frons pruinose or with large dust-spots and epistoma distinctly 

 pruinose; arista slightly pubescent; abdomen rather long.. 3. scalare. 



1. M. ambiguum Fall. 



1817. Fall. Dipt. Suec. Syrph. 47, 21 (Scaeva). — 1843. Zett. Dipt. 

 Scand. II, 757, 60 et 1849. VIII, 3153, 60 (Scaeva). — 1845. Stæg. Naturh. 



