194 ZOOLOGY. 



The MidasidcB contain a number of very large Diptera with clubbed 

 antennae. Midas filatus (black, with a transverse orange band near the 

 base of the abdomen) inhabits the United States. 



Leptis {fig. 116) is the representative of a family (Leptidcs) of small flies 

 of varied colors. In this genus the head is depressed, the antennae end in 

 a bristle, and the thorax is tuberculate. 



The Athericera contain the four families Syrphidce, in which the labium 

 incloses four setae ; Conopsidce, Muscida, having two setae ; and (Estridce, 

 with the mouth obsolete. 



The Syrphidce are tolerably large variously colored flies, which move 

 swiftly through the air, and often hover over a spot for some time without 

 changing their position. They have a hemispherical head, a great part of 

 which is taken up by the eyes, a soft rostrum elbowed towards the base, 

 with a pair of lip-like expansions at the tip, and the palpi small and 

 inarticulate. 



The genus Volucella (F. pellucens, pi. 77, fig. Ill) is remarkable 

 for its resemblance to the genus Bombus (bumble bee), which was 

 designed to enable it to reach without suspicion the nests of the 

 latter, in which the larvae are parasitic, feeding upon the larvae of 

 the bees. 



The eggs of Syi-pfnis are deposited among the Aphides, upon which the 

 larvae feed. Other larvae are vegetable feeders, and those of Eristalis (E. 

 tenax, fig. 114) and Helophilus {fig. 115) are aquatic, and have the pos- 

 terior part of the body attenuated into a breathing tube. These leave the 

 water to transform in the ground. Scceva pyrast7'i {fig. 112), Chryso- 

 toxum {fig. 113). 



The family Conopsidce {Conops macrocephala, fig. 90) are parasitic in the 

 nests of bees in the larva state, and the imagos frequent flowers. Latreille 

 reared a species which was parasitic in bees, and we have met with a living 

 grasshopper in Pennsylvania, with the abdomen filled with several dij)terous 

 larvae which we did not succeed in rearing. They may have belonged to 

 this genus, or to Tachinus. Latreille placed the genus Stomoxys {S. calci- 

 trans,fig. 91) in this family. 



The family Muscidce {figs. 101, 103, 106, 108) is very extensive, and 

 contains many minor groups. The habits of the species are very various. 

 Sarcophaga carnarici (fig. 109) deposits its larvae upon rotten vegetables, 

 caterpillars, and even on earthworms, which they penetrate, leaving their 

 posterior extremitf at the surface. Several genera deposit their eggs upon 

 flesh the moment it has become tainted ; and Tacliina and allied genera 

 resemble the IchneumonidcB in being parasitic in other living insects. 

 Musca domestica, the house fly, accompanies civilized man in his migra- 

 tions. The transformations of this species are said to take place in dung. 

 Various larvae attack different kinds of fruits, roots, and branches, causing 

 galls, and decaying vegetable matter of diflerent kinds. The larva of 

 Piopliila casei {fig. 103) infests cheese, and that of P. petasionis is found 

 in preserved hams. Both are known as skippers. The larvae of Oscanis 

 and Chlorops are destructive to growing grain. 

 398 



