858 • AN INTRODUCTION TO ENTOMOLOGY 



The currant fruit-fly, Epdchra canadensis. — The larva of this 

 species is a small white maggot which feeds within currants and goose- 

 berries. The infested fruit colors prema- 

 turely and usually falls to the ground. No 

 practicable method of controlling this pest 

 has been suggested. 



The round goldenrod gall. — One of the 

 most familiar of abnormal growths on 

 plants is a ball-like enlargement of the stem 

 of goldenrod (Fig. mi). This is caused by 

 Fig. II II. — The round a maggot, which lives within it, and which 

 goldenrod gall. develops into a pretty fly with banded 



wings ; this is Eurosta solidaginis. The larva 

 hibernates in the gall; the adult emerges in May. The gall of this 

 species is easily distinguished from that of the solidago gall-moth, 

 described in the preceding chapter, by its rounded form 



The family MICROPEZID^ is represented in America north of 

 Mexico by a few species; most of the species of this family occur in 

 vSouth America. In our representatives of the family, the subcostal 

 vein is distinctly separated from vein Ri ; cell R5 is closed or narrowed 

 at the margin; the head is subspherical; the buccas are broad; the 

 face is retreating; the vibrissae are wanting; and the proboscis is 

 short. 



The family TANYPEZID^ includes the genus Tanypeza, which 

 differs from the preceding family in that the buccce and the posterior 

 orbits are narrow. The described species are chiefly from South and 

 Central America. These flies are rare in the United States. 



The family SEPSID^ includes only a few species. These are 

 small slender flies, which are principally scavengers, feeding and 

 breeding in decaying organic matter. They are not rare, and can be 

 obtained by sweeping grass in meadows and pastures, especially 

 where there are droppings of horses and cattle. "Species of Sepsis 

 are particularly abundant and can be found on fresh dung, where 

 they run about with vibrating wings pirouetting in a unique and 

 pretty dance." 



The family has been monographed by Melander and Spuler ('17). 



Family PIOPHILID^ 



This family includes only a few species of small flies, rarely ex- 

 ceeding 5 mm. in length . They are usually glistening black or slightly 

 bluish metallic in luster. They are found about either decaying 

 organic matter, preserved meats, or cheese. The best known species 

 is the following. 



The cheese-maggot, Piophila cdsei. — This fly lays its eggs on 

 cheese, ham, and bacon. The larvag live in these substances and are 

 often serious pests. They are commonly known as "skippers" on 

 account of the remarkable leaps they can make. This is accomplished 

 by first bringing the head and tail ends together and then suddenly 

 straightening the body; in this way they can leap several inches. 



