202 Journal New York Entomological Society. [Vol. xvi. 



STUDIES ON MYRMECOPHILES. III. MICRODON. 



By William Morton Wheeler, 

 Boston, Mass. 



Few insects have occasioned more perplexity in the minds of ento- 

 mologists than the species of Microdon, or, more accurately speaking, 

 than the larvae and pupae of Microdon, for no tyro in entomology could 

 fail to recognize the imagines as Syrphid flies. So repeatedly have 

 even experienced observers been deceived by the singular elliptical 

 larvae and puparia, that the history of the genus is unusually instruc- 

 tive. The adult flies have been described under a variety of generic 

 names: Microdon (Meigen, 1803), Aphritis (Latreille, 1805), Cera- 

 tophya (Wiedemann, 1830), Chy mophila ( Macquart, 1834), Dimeraspis 

 (Newman, 1838), Mesophila and Ubristes (Walker, 1849 and 1856), 

 and, to add to the confusion, Conrad, in 1842, described a genus of 

 Silurian bivalves under the name of Microdon. The larva of the com- 

 mon European species, M. mutabilis, was first seen by von Heyden, 

 who in 1823 described and figured, but refrained from naming it. He 

 says that he does not believe it to be "the larva of an insect (perhaps 

 a species of fly) for its whole organizaation, especially the structure of 

 its mouth-parts, is too different from that of any insect larva" known 

 to him. So he concludes that "it is much more probably a mollusk, 

 but if such be the case, it must constitute a new and extraordinary 

 genus." The following year (1824) von Spix found the larva of the 

 same species of Microdon, and believing it to be a slug, named it 

 Scntelligera amerlandia. Thereupon von Heyden published a second 

 paper on the creature and dubbed it Parmula cocciformis, for the joy 

 of naming things was as great in the early decades of the nineteenth 

 century as it is to-day. The name cocciformis seems to have suggested 

 to Burmeister (1839) that the 'creature was the "larva of a Coccus 

 living on oaks"; at any rate, he enumerates it among the Coccidce. 

 The same year Schlotthauber presented to the German naturalists 

 assembled at Pyrmont a carefully written paperwith illustrations to prove 

 that the organisms described by von Heyden and von Spix as mollusks, 

 were really the larvae of Microdon mutabilis. Unfortunately this paper 

 was never published; a brief reference in Oken's " Isis " of 1840 

 being apparently the only record of its contents. In 1845 Elditt 



