DIPT ERA. 265 



at its apex as in the Tabanidae, or near its base as in 

 the (Estrid^. Fig. 216 represents the species Syr- 

 phus politiis, Say. Its larvae are without a distinct 

 head, the first ring being membranous. They devour 

 plant-Hce by sucking the fluids of the body, and their 

 mouth parts are therefore adapted for suction. The 

 fly lays its eggs among the aphides, so that the larvae 

 find their food within easy reach. Mrs. Mary Treat ^ 

 relates how an unlucky Syrphus happened in the way 

 of an ant. The ant took it in its mouth and shook 

 it " as a dog will shake a woodchuck." Eris talis 

 tenax, with its " rat-tailed larva," belongs to this family. 

 This " tail " is really a tube by means of which the 

 larva breathes while lying in water or concealed in 

 mud. 



MUSCID.^. 



The true house-fly, Musca domcstica, is much smaller 

 than several species of flies that are often seen indoors. 

 The scutellum of the mesothorax extends backward in 

 a blunt point, beneath which may be seen from behind 

 or from the side, if one wing and alulet are cut away, 

 the horny, shining posterior portion of the metathorax. 

 The mouth parts of this insect have already been briefly 

 described (see p. 252). Kraepelin- gives thirty-eight 

 beautiful figures illustrating the anatomy and physi- 

 ology of the proboscis, two of which are reproduced 

 by Packard.'^ 



The larvae (PL XII., Fig. 200), as we have already 



1 American Entomologist, Vol. II., p. 143, 



•^ Zeit.f. Wiss. ZooL, Vol. XXXIX., p. 683, 1883. 



^ See Entomology for Beginners, Figs. 137, 139. 



