156 INSECT ARCHITECTURE. 



these two properties have never been combined in 

 any of the tools of our carpenters. The rasping 

 part of the ovipositor, however, is not constructed 

 like our rasps, with short teeth thickly studded to- 

 gether, but has teeth almost as long as those of the 

 saw, and placed contiguous to them on the back of 

 the instrument, resembling in their form and setting 

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

 Of course, such observations are conducted with the 

 aid of a microscope. 



Portion of Saw jly's comb-toutlied rasp, ana 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 main- 

 tains 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 with- 

 drawn 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 glu- 

 ing 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 



