DIPTERA 



857 



Ortalidas. These two families can be separated by differences in ttie 



subcostal vein; in the TrypetidcX the distal part of the subcostal vein 



is abruptly turned forward and usually becomes very weak. In this 



family the vibrissse are wanting; 



the fronto-orbital bristles are 



numerous and extend down to 



the antennae; cells M and ist M2 



are separated by a cross-vein ; the 



legs are moderately long; the 



tibiae lack preapical bristles; and 



the ovipositor is flattened and 



more or less projecting. 



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. 



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. mo) 

 and the wings are crossed by four 

 dark confluent bands. The fe- 

 male punctures the skin of the 

 apple with her ovipositor and 

 lays her eggs in the pulp. The 

 larvse bores tunnels in all direc- 

 tions through the fruit. Early 

 maturing varieties of apples are 



Fig. mo. — The apple-maggot: /, lar- 

 va; 2, puparium; j, adult; la. head 

 of larva from side showing the oral 

 hooks and spiracle; ib, head of lar- 

 va from below; ic, caudal spiracle of 

 larva. 



especially attacked. When full-grown the larva goes into the ground 

 to transform where it hibernates in a brownish puparitmi. This is a 

 serious pest in the Eastern States and in Canada. This is a native 

 species, originally feeding in the fruit of wild thorn. It has been 

 found that most of the flies can be destroyed before they lay their 

 eggs by applying a spray of arsenate of lead, four pounds in one hun- 

 dred gallons of water, during the first week of July. The flies lap up 

 drops of moisture from the fruit and foliage and are thus poisoned. 

 The fallen apples should be collected or hogs allowed to nm in the 

 orchard. 



The cherry fruit-flies, Rhagoletis cinguldta and Rhagoletis fausta. 

 These two species, which are closely allied to the apple-maggot, infest 

 cherries, but not so commonly as does the pltun curculio. The cherry 

 fruit-flies can be destroyed by the use of the arsenate of lead spray 

 early in June. 



