ATTACKING THE LEAVES. 



285 



Fig. 295. 



No. 156. — The Grape-vine Saw-fly. 



Selandria vitis Harris. 



This is a small four-winged fly (Fig. 295), with a shining 

 black body, except the upper side of the thorax, which is 

 red ; the wings are semi-transparent, and have 

 dark-brown veins, the front pair being clouded, 

 or of a smoky color. The fore legs and under 

 side of the other legs are pale yellow or whitish. 

 The body of the female measures about three- 

 tenths of an inch in length, that of the male somewhat less. 

 The insect is double-brooded, the first brood of flies appearing 

 in the spring, the second late in July or early in August. 



The eggs are laid on the under side of the terminal leaves 

 of the vine in small clusters, and the larvae, when hatched, 

 feed in company, side by side, from about half a dozen to 

 fifteen or twenty in a group, preserving their ranks with 

 much regularity, as shown in Fig. 296. They begin at one 

 edge of the leaf and eat the whole of the 

 leaf — including the ribs — to the stalk, and 

 proceed from leaf to leaf down the branch, 

 devouring as they go, until they are full 

 grown. When mature, they measure about 

 five-eighths of an inch in length, are somewhat 

 slender and tapering behind, and thickened 

 before the middle. They are of a pale-yellow 

 color, darker or greenish on the back, with 

 two transverse rows of minute black points across each ring, 

 the head and tip of the last segment being black; the under 

 side is yellowish. After the last moult the larvae become 

 entirely yellow, when they leave the vines, descend to the 

 ground, and burrow under its surface. There they form oval 

 cells in the earth, which they line with silk, and within these 

 enclosures change to chrysalids, from which the perfect flies 

 escape in about a fortnight. The second brood pass the 

 winter in the chrysalis state. In Fig. 296 one of the oval 



Fm. 296. 



