354 AFFECTION OF INSECTS FOR THEIR YOUNG. 



Of the sources of exquisite gratification which every 

 rural walk will open to you, while witnessing in the 

 animals themselves those marks of affection for their 

 unseen progeny of Avhich I have endeavoured to give 

 you a slight sketch, it will be none of the least fertile 

 to examine the various and appropriate instruments 

 w^ith which insects have been furnished for the effective 

 execution of their labours. The young of the saw-fly 

 tribe (Tentkredo, L.) are destined to feed upon the 

 leaves of rose-trees and various other plants. Upon 

 the branches of these the parent fly deposits her eggs 

 in cells symmetrically arranged; and the instrument 

 with which she forms them is a saw, somewhat like ours 

 but far more ingenious and perfect, being toothed on 

 each side, or rather consisting of two distinct saws, with 

 their backs (the teeth or serratures of which are them- 

 selves often serrated, and the exterior flat sides scored 

 and toothed), which play alternately ; and, while their 

 vertical effect is that of a saw, act laterally as a rasp. 

 When by this alternate motion the incision, or cell, is 

 made, the two saws, receding from each other, conduct 

 the egg between them into it^. The Cicada, so cele- 

 brated by the poets of antiquity, which lays its eggs in 

 dry wood, reqi.ires a stronger instrument of a different 

 construction. Accordingly it is provided with an ex- 

 cellent double auger, the sides of which play alternately 

 and parallel to each other, and bore a hole of the re- 

 quisite depth in very hard substances without ever be- 

 ing displaced. 



The construction of the sting or ovipositor with 



* Prof. reck'3Nat.IIii>l.oftficSlus'Worm,l2.t.f. 12-14. PlateXV. 

 Tig. 21. 



