156 MISC. PUBLICATION 631, U. S. DEPT. OP AGRICULTURE 



Larvae. — The larva is a small white maggot of the muscoid type 

 with prominent tubercles on the last abdominal segment and with 

 stalked posterior spiracles, the stalks of which are contiguous at their 

 bases (fig. 93). 



DROSOPHILA MELANOGASTER Meigen 



The Pomace Fly 



Synonym. — Drosophila ampelophila Loew. 



Recognition Characteks. — Adult: The facial carina is prominent; the cheeks 

 are narrow, their greatest width being about one-fifth the greatest diameter of 

 the eyes. The mesonotum is yellow and unmarked; the pleura likewise yellow, 

 without a dark stripe or spots. The acrostical hairs are in 8 rows. The male 

 has a comb of short stout bristles on the anterior basitarsus. The abdomen is 

 black, with a broad yellowish band on each of the first three segments ; these 

 bands may be obscure in the female. Length about 2 mm. Larva (fig. 93, A) : 

 This is a rather robust larva, about 5-6 mm. in length. The last 10 segments 

 bear fusiform areas of spines ventrally, although the first and sometimes also 

 the second segments are not easily seen. The posterior spiracles are light yellow ; 

 the posterior end of the body before the spiracles is truncated and rather hairy. 



Geographical Distribution. — Widespread through the warmer and temperate 

 parts of the world. Neartic Region : Nova Scotia, Quebec, Ontario, British 

 Columbia, Maine, New Hampshire, Vermont, Massachusetts, Rliode Island. Con- 



Figure 93. — A, Drosophila melanogaster, terminal abdominal segments of larva; 

 B, D. funebris, same. (After Keifer (64, p. 576).) 



necticut, New York, New Jersey, Pennsylvania, Maryland, District of Columbia, 

 Virginia, West Virginia, North Carolina, South Carolina, Georgia, Florida, Ala- 

 bama, Mississippi, Tennessee, Ohio, Indiana, Illinois, Minnesota, Wisconsin, 

 Missouri, South Dakota, Kansas, Arkansas, Louisiana, Oklahoma, Texas, Mon- 

 tana, Idaho, Wyoming, Colorado, Utah, Nevada, New Mexico, Arizona, Washing- 

 ton, Oregon, California. Neotropical Region : Mexico. British Honduras, Costa 

 Rica, Panama, Canal Zone. Bermuda, Bahama Islands, Cuba, Jamaica, Dominican 

 Republic, Puerto Rico, Barbados, Ecuador, Brazil, Peru, Bolivia, Uruguay, Chile, 

 Argentina. Palaearctic Region : Ireland, England, Spain, France, Netherlands, 

 Italy, Sicily, Sweden, Finland, Germany, Austria, Hungary, European Turkey, 

 European Russia (northward to Arkhangelsk), Azores, Algeria, Libia, Egypt, 

 Japan. Oriental Region : Malaya, Taiwan, Philippine Islands. Ethiopian Re- 

 gion : Mozambique, South Africa. Australian Region: South Australia, New 

 South Wales, New Zealand, Samoa. Fiji, Marquesas, Hawaiian Islands. 



Biology and Pathogenesis. — This is the fly so well known to 

 geneticists. The larvae breed in a wide variety of overripe fruits, as 

 well as stale beer, and, very exceptionally, human excrement. Females 

 have been known to oviposit when a clay old, but oviposition and 

 mating usually take place the second or third day. Development is 

 very rapid, usually being completed under laboratory conditions in 

 8 to 12 clays. It is doubtful whether it can hibernate in the cooler 

 parts of its range, but the supply is easily restocked from shipped-in 

 fruits. 



