416 INSECTS INJURIOUS TO VEGETATION. 



a little more than three twentieths of an inch long, that of the 

 female one fifth of an inch or more, and the wings expand 

 nearly or quite two fifths of an inch. These saw-flies come 

 out of the ground, at various times, between the twentieth of 

 May and the middle of June, during which period they pair 

 and lay their eggs. The females do not fly much, and may 

 be seen, during most of the day, resting on the leaves ; and, 

 when touched, they draw up their legs, and fall to the ground. 

 The males are more active, fly from one rose-bush to another, 

 and hover around their sluggish partners. The latter, when 

 about to lay their eggs, turn a little on one side, unsheathe 

 their saws, and thrust them obliquely into the skin of the leaf, 

 depositing, in each incision thus made, a single egg. The 

 young begin to hatch in ten days or a fortnight after the eggs 

 are laid. They may sometimes be found on the leaves as early 

 as the first of June, but do not usually appear in considerable 

 numbers till the twentieth of the same month. How long 

 they are in coming to maturity, I have not particularly ob- 

 served ; but the period of their existence in the caterpillar 

 state probably does not exceed three weeks. They somewhat 

 resemble young slug-worms in form, but are not quite so con- 

 vex. They have a small, round, yellowish head, with a black 

 dot on each side of it, and are provided with twenty-two short 

 legs. The body is green above, paler at the sides, and yellow- 

 ish beneath ; and it is soft, and almost transparent like jelly. 

 The skin of the back is transversely wrinkled, and covered 

 with minute elevated points ; and there are two, small, triple- 

 pointed warts on the edge of the first ring, immediately behind 

 the head. These gelatinous and sluggish creatures eat the 

 upper surface of the leaf in large irregular patches, leaving the 

 veins and the skin, beneath, untouched ; and they are some- 

 times so thick that not a leaf on the bushes is spared by them, 

 and the whole foliage looks as if it had been scorched by fire, 

 and drops off soon afterwards. They cast their skins several 

 times, leaving them extended and fastened on the leaves ; after 

 the last moulting they lose their semitransparent and greenish 

 color, and acquire an opake yellowish hue. They then leave 

 the rose-bushes, some of them slowly creeping down the stem, 



