SAW-FLIES. 137 



teeth of a comb, as may be seen in the figure. Of course, 

 such observations are conducted with the aid of a micro- 

 scope. 



Portion of Saw-fly's comb-toothed rasi), and saw. 



When a female saw-fly has selected the branch of a 

 rose-tree, or any other, in which to deposit her eggs, she 

 may be seen bending .the end of her belly inwards, in 

 form of a crescent, and protruding her saw, at the same 

 time, to penetrate the bark or wood. She maintains this 

 recurved position so long as she works in deepening the 

 groove; but when she has attained the depth required, 

 she unbends her body into a straight line, and in this 

 position works upon the place lengthways, by applying 

 the saw more horizontally. When she has rendered the 

 groove as large as she wishes, the motion of the tendons 

 ceases, and an egg is placed in the cavity. The saw is 

 then withdrawn into the sheath for about two-thirds of 

 its length, and at the same moment a sort of frothy 

 liquid, similar to a lather made with soap, is dropped over 

 the egg, either for the purpose of gluing it in its place or 

 sheathing it from the action of the juices of the tree. She 

 proceeds in the same manner in sawing out a second 

 groove, and so on in succession, till she has deposited all 

 her eggs, sometimes to the number of twenty-four. The 

 grooves are usually placed in a line, at a small distance 

 from one another, on the same branch ; but sometimes 

 the mother-fly shifts to another, or to a different part of 

 the branch, when she is either scared or finds it unsuitable. 

 She commonly, also, takes more than one day to the work, 

 notwithstanding the superiority of her tools. Eeaumur has 

 seen a saw-fly make six grooves in succession, which occu- 

 pied her about ten hours and a half. 



The grooves, when finished, have externally little 



