Dec, i 9 o8.j Wheeler : Studies on Myrmecophiles. 203 



endeavored to make good this loss to science in an excellent article on 

 the metamorphosis of the insect. But the resemblance of the larval 

 Microdon to a naked mollusk has contined to breed new generic names 

 down to the present day. Prof. T. D. A. Cockerell calls my atten- 

 tion to a recent article by Simroth (1907), in which he describes 

 what is evidently the puparium of a Microdon or of some allied Syrphid 

 genus, from Cape Flats, South Africa, as a new genus and species of 

 slug (Ceratoconche schuitzei) to be placed "between the genera Tcs- 

 tacella and Apera." Simroth actually interprets the posterior tubercle 

 of the puparium as a vestigial shell ! There is apparently no reason why 

 unusual Microdon larva? and pupa.', as fast as they are brought to light 

 in various parts of the world, should not become the types of futile 

 genera of naked mollusks, at least till the millennium arrives, when 

 naturalists no longer itch to attach a name to everything that swims 

 within their ken. 



The genus Microdon embraces about 70 described species, and 

 seems to be cosmopolitan in its distribution. Many of the species, 

 however, are highly variable and have been but little studied, so that 

 it is impossible at present to give more than a general account of their 

 number, range and habits. According to Schiner (1864) and Verrall 

 ( 1901), there are only three or four species in Europe. Aldrich (1905) 

 enumerates 28 from North America. Lea (1893) has found the larvae 

 of a form, which he calls M. variegatus, in New South Wales. Sim- 

 roth, as we have seen, has described the puparium of a South African 

 species, and several have been recorded from South and Central 

 America and Madagascar (Sharp, 1899 ; Wasmann, 1894). 



The larval and pupal stages of these singular insects are found 

 only in the nests of ants, wasps and termites. Wasmann ( 1890) 

 seems to be the only author who has seen them in wasp nests. In his 

 list of myrmecophiles and termitophiles (1894) he mentions their 

 occurrence also in the termitaria of Madagascar and Brazil. Most 

 frequently, however, both in temperate and tropical regions, the 

 larvae and puparia are found living with ants. In these stages the 

 insects are gregarious, as a rule, so that several may be seen clinging 

 to the walls of the galleries and chambers. They seem to live indif- 

 ferently in nests in the soil, under stones, under the bark of trer^ or 

 in the cavities of branches. The larva;, while young or partially 

 grown, often inhabit the deeper recesses of the nests, but when they 

 reach maturity and are ready to pupate, they emigrate to the surface 



