DIPTERA 



3i5 



tures (Fig. 557), which resemble mollusks more than ordinary maggots; 



they are common in ants' nests. 



The larvae of several species that live in water as well as some that 



live in rotten wood are known as rat-tailed mag- 

 gots on account of the long, tail-like, air-tube with 



which the hind end of the body is furnished. This 



tube enables the insect to obtain air when its body 



is submerged beneath several inches of water or Fl ^. ss7-—Microdon, adult 



decaying matter. This tube being telescopic can 



be lengthened or shortened as the insect may need it; and at its tip 



there is a rosette of hairs, which, floating on the surface of the water, 



keeps the tip from being submerged. 



One of these " rat-tailed " maggots is the larva of the drone-fly, 

 Eristalis tendx. The maggot lives in foul water but obtains 

 good air through its air-tube which projects up to the sur- 

 face. The adult fly resembles a male honey-bee. 



Among the more common members of this family are the 



yellow-banded species belonging to the genus Syrphus (Fig. 



fig. 558. — 55&)- The larvae of these live in colonies of aphids and do 



Syrphus. good by destroying these pests. 



SERIES II. CIRCULAR-SEAMED FLIES WITH A FRONTAL SUTURE. 



(Schizophora) 



The flies of the next eight of these families with a frontal suture have 

 very small or rudimentary alula or calypteres. They are therefore known 

 as acalyptrate flies or muscids. 



Family Ortalid^ 



This family like the Trypetidae is a large one and contains many com- 

 mon species which have the wings beautifully marked with dark spots or 

 bands. 



Comparatively few species of the Ortalidae have been bred and these 

 differ greatly in habits. The larvae of some have been found under bark 

 of dead trees, others in excrement, some are parasitic on lepidopterous 

 larvae, and several infest growing plants. Among the latter are Chaztopsis 

 (Bnea and Tritoxa flexa which sometimes infest onions. 



Family Trypetidae 



This is a very large family including many common species with 

 pictured wings, in which it resembles the preceding family, the Ortalidae. 



The larvae of the species that have been bred infest living plants. 

 Some are leaf-miners, some live in the stems of plants, some make galls, 

 and some are pests that infest fruit. Among the better-known species 

 are the following so-called fruit-flies. 



The apple-maggot, Rhagoletis pomonella. — The adult is blackish with 

 the head and legs yellowish; the abdomen is crossed by three or four 

 white bands (Fig. 559) and the wings are crossed by four dark confluent 

 bands. The female punctures the skin of the apple with her ovipositor 

 and lays her eggs in the pulp. The larvae bore tunnels in all directions 



