INSECTS : STINGS AND OVIPOSITOKS. 155 



same time, to penetrate tlie bark or Avood. 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 bodj into a straight 

 line, and in this position works upon the place length- 

 ways, by applying the saw more horizontally. When 

 she has rendered the groove as large as she wishes, the 

 motion of the tendon ceases, and an egg is placed in 

 the cavity. The saw is tlien withdrawn into the sheath 

 for about two-thirds of its length, and at the same mo- 

 ment, a sort of frothy liquid, similar to a lather made 

 with soap, is dropped over the egg, either for the pur- 

 pose 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, some- 

 times 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. 

 Reaumur has seen a Saw-fly make six grooves in suc- 

 cession, which occupied her about ten hours and a- 

 half. 



" Tlie 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 the part becomes first brown 

 and then black, while it also becomes more and more 

 elevated. This increased elevation is not owing to the 

 growth of the bark, the fibres of which, indeed, have 



