THE WILLOW CIMBEX. 



585 



of the eggs could be found either ou the dead part of the twig or in the living por- 

 tion just beneath. The eggs are deposited between the epidermis and paranchyma 

 of the leaf. When looking over the plants from above, the place of oviposition is 

 hardly perceptible, appearing as a very slight blister-like swelling, accompanied on 

 one side by a faint ferruginous line, but otherwise not differing in color from the rest 

 of the leaf. On the under side, however, these blisters were very plainly visible, 

 being much paler than the rest of the leaf, and having, in the more developed con- 

 dition, a reddish tinge. These blisters closely resemble those of other saw-flies, 



Fig. 194.— Cimbex of the willow : a, leaf containing the eggs ; b, willow twig with incisions ; c, egg ; 

 d, young larva; e, mature larva; / cocoon; g, the same cut away to show the pupa, h; k, saw of the 

 fly, i. After Riley. 



which insert their eggs in leaves and are usually nearly circular in outline (some- 

 times nearly oval), and distinctly elevated above the general surface of the leaf, 

 though otherwise quite flat. They are always on the face of the leaf, usually nearer 

 to the outer margin than to the midrib, never on or near the midrib and rarely 

 extending across one of the side ribs. Their number varies from one to nine or more 

 on a single leaf. Where there are several they are generally situated in a longitudi- 

 nal row, the individual blisters being then always separated by the intervening side 



