325 

 Family Drosophilidse— The Small Fruit Flies 



Small flies, rarely exceeding a length of 5 mm. the head sometimes 

 very broad, the wings often pictured. 



Face nearly vertical in profile, rarely prominent, oral vibrissse 

 present, though sometimes weak; front with three pairs of bristles; post- 

 ocellar bristles convergent, rarely absent. Third antennal segment oval 

 or rounded, the basal two short; arista usually plumose, rarely pubescent 

 or with a single long ray. Abdomen usually short, rather elongate and 

 pendulous in Curtonotum. Auxiliary vein usually very short and end- 

 ing in the first vein; costa broken twice; first vein short; second basal 

 cell usually united with the discal cell; anal cell present, rarely in- 

 complete. 



The adults are found around decaying vegetation, flowing sap, fungi 

 and ripe fruit, the larvae being found in these substances. They are 

 often pests to the housewife, since they apparently appear from no- 

 where when fruit is brought into the house and some of the fungus 

 inhabiting species have the habit of hovering around the eyes during 

 warm weather, causing not only irritation by their antics but pain 

 when they get into the eye. In the tropics they sometimes occur in 

 such numbers as to completely cover large fungi. There have been 

 frequent complaints about them in milk bottles, the puparia becoming 

 attached to the bottles and requiring special treatment for their re- 

 moval. 



One of the species, DrosopJtiJa melanogaster Meigen, has been used 

 extensively for the study of inheritance, being exceedingly well suited 

 for tliis purpose because of the very short life cycle and large chromo- 

 somes. The general belief has been that the larva? live upon fruit but it 

 has been shown that they actually live upon the yeasts developing in it. 



Sturtevant* has reviewed the North American species and Dudaf 

 has dealt with the Neotropical forms. In addition there are numerous 

 small i)apers scattered through the literature. In addition to the genera 

 given in the key several others, as well as a number of subgenera, have 

 been proposed but most of them appear to be too poorly differentiated 

 to deserve recognition. Aldricht has discussed the occurrence in North 

 America of the genus Lciom]jza ]\[acquart and described two species. 

 As I have no specimens I am unable to place the genus in the key. 

 Sturtevant* has referred this genus to the Asteiida^ but this disposition 

 of it does not agree with my interpretation of that family. 



* 1921. The North American Species of Drosoiihila, Carneprie Inst, of Wash., pub. No. 

 301, 150 pp. 



tl927. Die Sudamerikanischen Drosoiihiliden, etc., Arch fiir Natursesichte, 1925, Hefts 

 11-12, pp. 1-229. 



t 1919. Ent. News, xxx, p. 137. 



