156 EVENINGS AT TBCE MICEOSCOPE. 



been destroyed by tbe ovipositor-saw, but to the actual 

 growth of the egg ; for, when a new-laid egg of the 

 Saw-fly is compared with one which has been several 

 days inclosed in the groove, the latter will be found to 

 be very considerably larger. This growth of the egg is 

 contrary to the analogy observable in the eggs of birds, 

 and even of most other insects ; but it has its advan- 

 tages. As it continues to increase, it raises the bark 

 more and more, and consequently widens, at the same 

 time, the slit at the entrance ; so that, when the grub is 

 hatched, it finds a passage ready for its exit. The 

 mother-fly seems to be aware of this growth of her eggs, 

 for she takes care to deposit them at such distances as 

 may prevent their disturbing one another by their 

 development." * 



The merry little jumping insects called Frog-hop- 

 pers {Tettigonia), one of which in its larva state emits 

 the little mass of froth so common on shrubs, and called 

 cuckoo-spit, are furnished with a set of tools for their 

 own private carpentry, which, though less elaborate 

 than those of the saw-flies, are worthy of a moment's 

 glance. If we catch one of these vaulters and gently 

 press the abdomen, we shall see proceeding from its 

 hinder and lower part, a thickish piece, large com- 

 pared with the size of the insect, which it is then 

 easy to extract with a pair of fine pointed pliers. I 

 have just done this, and here is the result on a slip of 

 glass. 



First there is a pair of brown protecting pieces, ob- 

 long in form, and studded with hairs like the rest of 

 the. exterior of the body. From between them projects 

 what resembles a lancet, of the usual translucent amber- 

 * Insect Architecture, 155. 



