486 THE STUDY OF INSECTS. 



tinct. The two following are well-known members of the 

 Trypetinse. 



The Apple-maggot, Trypeta pomonclla (Try-pe'ta pom-o- 

 nel'la.) This maggot eats into the pulp of apples, boring 

 tunnels in all directions through the fruit ; it attacks espe- 

 cially the early maturing varieties. When full-grown it goes 

 into the ground to transform. The adult is a black and 

 white fly, with banded wings (Fig. 592). 



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. 593). 

 This is caused by a maggot, which 

 lives within it, and which develops 

 into a pretty fly with banded wings. 

 This is Trypeta solidaginis (T. Sol-i- 

 dag'i-nis). There is another gall on 

 FIG. 593. The Round Golden- the stem of goldenrod which is liable 



rod Gal). ... , . . . , 



to be mistaken for this one, but which 



can be easily distinguished from it. It is more elongate, 

 and is hollow. It is made by the larva of a Tineid moth, 

 Gcleckia gall&solidaginis (Ge-le'chi-a gal-lae-sol-i-dag'i-nis) ; it 

 maybe called the Elliptical Goldenrod Gall. 



The Stem-eyed Fly, Sphyracephala brevicornis (Sphyr-a- 

 ceph'a-la brev-i-cor'nis) is a very singular fly, which is found 

 on the leaves of skunk-cabbage. On each side of the head 

 there is horn-like process extending outward, upon the end 

 of which the eye is situated. This species is the only Amer- 

 ican representative of its subfamily, the Diopsintz (Di-op- 

 si'nae), yet described. 



The Cheese-maggot, PiopJiila casci (Pi-oph'i-la ca'se-i) is 

 the larva of a small black fly, less than half the size of the 

 House-fly. It belongs to the small subfamily PiophilincB 

 (Pi-oph-i-li'nae), in which vein II of the wings is quite closely 

 united with vein III. This fly lays its eggs on cheese, ham, 

 and bacon ; the larvae live in these substances and are often 

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



