582 Syrphidae. 



The species of Microdon are rather curious, somewhat robust 

 flies, with some resemblance to the hive-bee. They are recorded to 

 occur on humid meadows, flying in the grass with the abdomen pen- 

 dulous, and they produce a humming noise. 



Of the genus 6 species are recorded from the palæarctic region, 

 but of these only 4 are found in Europe ; 3 have been found in Den- 

 mark. In 1912 Andries has, in the work cited above, founded a fifth 

 European species, rhenanus; this species is, however, seen to be very 

 near to niutabilis, both as imago and in the developmental stages so 

 that I am inclined to doubt its distinctness ; its biology is also seen 

 to be the same as for mutabilis, the larva occurring only with F. fusca ; 

 the length is by Andries for rhenanus given to 9 mm, for mutahilis 

 to 12 mm, but the length of the latter is otherwise generally given to 

 9 — 12 mm, and I have found it to be 8 — 10,5 mm so that this 

 character is of no value. Also it is no good method to introduce a 

 new species with only a few words, especially in a genus, the species 

 of which are not quite well known. 



Tahle of Species. 



1 . Scutellum brownish red 1 . mutahilis. 



— Scutellum æneous 2. 



2. Thorax with a patch of black hairs on the disc between the 

 wing-roots ; scutellum with the spines not specially small, 



tbe margin between them concave 2. devius. 



— Thorax all yellow-haired ; scutellum with very small spines, 



the margin between them straight 3. Eggeri. 



1 . M. mutabilis L. 



1758. Linn. Syst. Nat. X, 592 et 1767. XII, 2, 985, 40 et 1761. Fn. 

 Suec. 1807 {Musca). — 1775. Fabr. Syst. Entom. 767, 24 {Syrphus) et 1805. 

 Sysl. Antl. 184, 4 {Mulio). — 1816. Fall. Dipt. Suec. Syrph. 4, 1. — 1822. 

 Meig. Syst. Beschr. III, 164, 2. — 1843. Zett. Dipt. Scand. II, 642, 2. — 

 1862. Schin. F. A. I, 250. — 1899. Mik, Wien. ent. Zeitg. XVIII, 141. — 

 1901. Verr. Brit. Fl. VIII, 660, 1, figs. 451—453. — 1907. Kat. palåarkt. 

 Dipt. III, 1 55. — Aphritis apiarius Latr. 1 804. Diet. Hist. nat. Déterv. XXIV, 

 193, 564. — 1805. Fabr. Syst. Antl. 185, 9 {Mulio). — Musca apiformis 

 De Geer, 1776. Mém. Ins. VI, 128, 18, Tab. VII, fig. 18—20. — 1822. 

 Meig. 1. c. III, 163, 1 et 1830. VI, 349 {Microdon). — 1856. Loew Verh. 

 zool. bot. Gesell. Wien, VI, 600 {Microdon). 



Male. Vertex and frons æneous green, shining, punctate; frons 

 at its narrowest point with an impressed and impunctate transverse 

 line; vertex and frons with yellow hairs, which are erect above the 

 impression but below it are declining forwards; above the antennæ 

 is a triangular, bare space; epistoma æneous green, densely covered 



