172 Insect Architecture. 



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 together, but has 

 teeth almost as long as those of the saw, and placed con- 

 tiguous 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. 



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 pene- 

 trate 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 The saw is then withdrawn into the sheath for 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 com- 

 monly, also, takes more than one day to the work, notwith- 

 standing the superiority of her tools. Reaumur has seen a 

 saw-fly make six grooves in succession, which occupied her 

 about ten hours and a half. 



The grooves, when finished, have externally little elevation 

 above the level of the bark, appearing like the puncture of a 

 lancet in the human skin ; but in the course of a day or two 



