FAMILIES GEOMYZID/E, AGROMYZIDy^ 

 AND BORBORIDyE 



The family Geomyzid^ is a small one, and is composed of 

 very small flies about which there is nothing especially distmcUve 

 or especially interesting. ^ 



They are usually rather 

 slender and of a grayish or 

 yellow color, looking some- 

 thing like the pomace flies. 

 Those of which the meta- 

 morphoses are known have 

 larva which mine the leaves 

 of grasses and grains. 



The Agromyzid flies, 

 as a rule, are small, insig- 

 nificant creatures of dull 

 colors. The larvae of some 

 of them feed on living 

 plants, forming burrows or 

 mines in various parts, and 

 especially in the leaves, 

 while the larvae of others 

 (of the genus Leiicopis) 

 prey upon plant-lice and scale insects. None of the species, 

 however, appear to have any great economic importance. 



The Borborida are little flies, usually of dark color, and with 

 clear wings. They are often to be found in great numbers upon 

 dung, and, in fact, appear to breed exclusively in this substance. 

 One of the species of the genus Umosina (L. -venalicnis) was 

 found abundantly in Cuba by Osten Sacken, and as it is an 

 African species it is very probable that it was brought over in 

 slave ships. The flies of this family have some value on account 

 of their function as scavengers, but they may be responsible for 

 the spread of disease among human beings. 



187 



Fig. 108. — Sphaerocera subsultans. 

 (Atithor's illustration.) 



