ORDER DIPTERA 265 



the leaf, although the comparative thinness of the leaf makes 

 them slightly visible from the lower surface also. The mines 

 are whitish in color and the frass is scattered in small spots 

 and is not conspicuous. Sometimes the larvae produce 

 blotch mines. European workers refer to this species as a 

 blotch-miner. 



The full grown larvae abandon their mines to transform. 

 They make their exit through a semicircular slit at the end 

 of the mine, on the under surface of the leaf. The puparia 

 are exceptionally small, football-shaped, dark colored and 

 look very much like seeds. 



The adults, like many of the agromyzidae, make circular 

 punctures in the leaves with their ovipositors and through 

 these punctures they suck the juices of the plant. The 

 punctures later become whitish in color, and are as con- 

 spicuous as the mines themselves. 



DROSOPHILIDAE 



The small flies of this family are closely related to the Ag- 

 romyzidae and the Ephydridae. The leaf -mining species 

 are yellowish or light colored and the bristles of the front 

 are conspicuous. The larvae of the Drosophilidae are 

 mostly scavengers feeding on decaying or fermenting fruits, 

 vegetables or other refuse. The appearance of the leaf- 

 mining habit in this family is unusual and represents a habit 

 that is not entirely established. While some of the species 

 have adapted themselves to the leaf -mining habit, they can 

 also be bred through several generations on tomato fruits or 

 potato tubers showing that they have not entirely departed 

 from their scavenger habits. The leaf -mining species be- 

 long to the genus Scaptomyza. 



Scaptomyza 



The species of this genus have been badly mixed up in 

 literature. There are apparently three North American 



