526 HYMENOPTEEA. 



eggs, turn a little on one side, unsheathe their saws, and 

 thrust them obliquely into the skin of the leaf, depositing, 



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



,. | young (Fig. 246) begin to hatch in ten days 



*$# > MP^ 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 20th of the same month. How long they are in 

 coming to maturity, I have not particularly observed; 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 convex. 

 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 yellowish beneath; and it is soft, and almost trans- 

 parent, 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 semitrans- 

 parent and greenish color, and acquire an opaque yellowish 

 hue. They then leave the rose-bushes, some of them slowly 

 creeping down the stem, and others rolling up and dropping 

 off, especially when the bushes are shaken by the wind. 



Fig. 247 Having reached the ground, they burrow to the 



<$gij§bki depth of an inch or more in the earth, where 



each one makes for itself a small oval cell (Fig. 



24T), of grains of earth, cemented with a little gummy silk. 



