THE FRUIT AND GALL FLIES 



(Family Trypetidce.) 



Most of the flies of this family are rather small, although 

 some are above medium size. They are of very striking appear- 

 ance and interesting habits. They vary from light yellow in 

 color to dark brown or nearly black, and the body is frequently 

 curiously spotted in the lighter specimens. The wings are also 

 beautifully banded and 

 marked. The group is 

 a large one and is well 

 represented in the United 

 States, many genera and 

 species occurring withus. 



The Trypetid flies 

 in their early stages live 

 in fruits or in the stems 

 of plants, producing 

 galls. The so-called 

 apple maggot of the 

 Northeastern States, an 

 insect which is especially 

 abundant in Maine and 

 New Hampshire, is the larva of Rhagdetis pomonella. It eats 

 into the pulp of apples, boring tunnels in all directions through 

 the fruit. It is said especially to attack the earlier ripening 

 apples. When full grown it drops to the ground and transforms 

 within the last larval skin. The adult insect is a black and white 

 fly with banded wings. One of the large round galls which 

 occurs upon the stems of goldenrod is made by one of these flies 

 known as Eurosta asteris. There are sometimes two of 

 these galls on the same stalk, and they are most conspicuous in 

 the winter time when there are no leaves on the plant. If one 

 cuts open one of these galls it is found to be full of a pithy solid 



177 



Fig. 1 01. — Tephritis asqualis. (After Marlatt.) 



