4§6 THE STUDY OF INSECTS. 



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

 Trypetinse. 



The Apple-maggot, Trypeta pomonella (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 

 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, 

 Gelechia gallcesolidaginis (Ge-le'chi-a gal-lae-sol-i-dag'i-nis) ; it 

 may be called the Elliptical Goldenrod Gall. 



The Stem-eyed Fly, Sphyracephala brevicomis (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 Diopsince (Di-op- 

 si'nae), yet described. 



The Cheese-maggot, Piophila casei (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 Piophilince 

 (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 



