34° 
The Two-winged Flies 
don, which live in ants’ nests, look like little mollusks, and when first found 
were actually described as new molluscous genera. Their body is flat, 
Fig. 480.—Rat-tailed larva of a Syrphid. (Twice natural size.) 
Fig. 481.—-Larva of Microdon mutabilis, dorsal view. (Four times natural size.) 
broad, unsegmented, and looks like a flat broadly elliptical little shell or 
plant-seed (Fig. 481). 
Among the more common flies of this family which may be taken by the 
collector are various species of Eristalis, with black, yellow, and amber colors, 
heavy-bodied, bee-like forms, and especially E. tenax, the drone-fly, which 
resembles very much a honey-bee drone. Its larva is a rat-tailed maggot. 
The species of Syrphus are black with yellow bands, with the abdomen 
not so heavy as in Eristalis. The larvae are predatory, doing great havoc 
in aphid colonies, but being thus of great benefit to florists and gardeners. 
Fig. 482.—Mouth-parts of Eristalis sp. li., labium; hyp., hypopharynx; lb., labrumj 
mx., maxilla; mx.l., maxillary lobe; mx.p., maxillary palpus. 
The species of Volucella are bee-like in appearance and their larvae live in 
the nests of bees, but whether as parasites or tolerated guests seems not 
to be yet known. Sharp thinks that they act as scavengers in the nests, 
and thus are helpful rather than harmful to their hosts. Syritta pipiens is 
a common Syrphid fly, with slender, elongate, subcylindrical body, blackish 
with reddish-yellow markings. 
