66 STRATIOMYID.E 



from Hobart, Tasmania. Macquart's P. rufitarsis from Pondicherry does 

 not (according to his figure of it) belong to tliis subfamily, but more 

 likely to the Sargince. Only five well-distinguished species are known to 

 occur in Europe, all of which are now recorded from Britain, Scandinavia, 

 and Germany. The metamorphoses are unusually well known as all the 

 species have been bred, and in fact some of the species are much more 

 easily found as larvse or pupse than as imagines. The larvae have been 

 found in the rotten part of decaying trees and possibly feed on the decayed 

 wood, but more probably on the detritus and frass caused by wood-boring 

 Coleoptera. Notes upon this subject are given under each species and 

 especially under P. orhitalis, and attention is drawn to the frequency of 

 each species affecting its own particular kind of tree, or possibly the 

 Coleoptera which affect particular kinds of trees. Perris considered the 

 larvse to be closely allied to those of Sargus, while Austen has considered 

 them allied to Bcri-'^. In the perfect insects the venation is very similar 

 to that of Bcris, while the antennce are allied to those of the Sarginm, and 

 more especially to those of the genus Microchrysa. 



Synonym,]/. — Pachygaster has been a well-recognised lioniogeneous genus for nearly 

 a century, biit in 1901 Austen proposed a new genus JVeopachyf/aster for a species 

 which he called JV. meromelwna Perris, but which I recognise as P. orhitalis Wahl- 

 berg ; the only distinctive characters given by him are the separated eyes in both 

 sexes, and the posterior orbits not produced into a prominent ridge in either sex, 

 but I can only consider these characters as of siDecihc value, especially as Austen 

 suggests that P. Leachii might possibly be separated generically from P. atra, and 

 Dr Sharp hints at another genus for P. mimitissima, which would leave only P. atra 

 and P. tarsalis in true Pachygaster, and as these two species differ remarkably^ in 

 the shape of the head and eyes we should soon have a genus for each species. 

 Aldrich (Cat. N. Amer. Dipt. 192) has indicated a North American species which 

 would apparently agree with Neopachygaster. The type of the genus must be 

 P. atra Panzer, and Meigen claimed priority for the name Pachygaster (1803) over 

 VapiJO Latreille (1804). 



Tabic of Species. 



1 (2) Cubital vein not forked (fig. 91). 1 mimitissima. 



2 (1) Cubital vein forked (fig. 94). 



3 (6) Wings with the basal half blackish when contrasted with the 



apical half. 



4 (5) Antennae dull black in the male, bright ochre in the female. 



5 (4) Antennae reddish at the base, but with the third joint darkened in 



both sexes. S^t-UxXtu-m *^'»'«"«^A^ ^ 'Aaa^ ai-'Vv-n 3 tarsalis. 



6 (3) Wings entirely hyaline. 



7 (8) Femora black except at the extreme tip. 4 orhitalis. 



8 (7) Femora yellow except for a blackish ring near the tip of the hind 



pair. 5 Leachii. 



1. P. minutissima Zetterstedt. Cubital vein not forked, but strongly 

 up-curved so that it ends near the radial vein. 



The smallest European species of the genus ; easil}^ dis- 

 tinguished ]iy the absence of any fork to the short up-curved 



