62 INSECTS AND MAN 



the supporting piece, and their serrated edges are the chief 

 agents in piercing the twigs preparatory to oviposition. 

 The blades are operated by powerful muscles, in making 

 incisions in the twigs, and the eggs pass through the tube 

 formed by the three pieces of the instrument, till they 

 reach their resting place in the twig. 



The act of oviposition may easily be observed in these 

 insects; when about to oviposit, the female always takes 

 up a position with her head towards the end of a branch, of 

 such a size that she may firmly clasp it with her legs. The 

 ovipositor is brought into operation at an angle of about 

 forty-five degrees, and it is thrust slowly into the bark and 

 wood. When fully inserted, the ovipositor is raised up- 

 wards, in order to prise up little wood fibres, which form a 

 sort of covering for the egg-fissure. Space is made to hold 

 ten to twenty eggs ; then the female returns to the starting 

 point and inserts the eggs in the twigs, in pairs, separated 

 by a tongue of wood which has been left undamaged. The 

 whole operation of filling a double nest lasts about forty- 

 five minutes. As many as fifty egg-nests may be found on 

 a single twig ; in fact, the female continues making the nests 

 till she has exhausted her store of eggs, which may number 

 from five to six hundred, then, worn out with her exertions, 

 she falls to the ground and dies. The eggs are exceedingly 

 delicate and slightly curved ; so thin and transparent is the 

 shell that, before hatching, the larva can be plainly seen 

 within. A certain amount of nourishment is absorbed by 

 the eggs from the juices of the plant cells, resulting in an 

 increase in size. In about six or seven weeks the larva 

 (fig. 10, A), by dint of much wriggling and twisting, frees 

 itself from its shell and a delicate membrane which covers 

 it, and then, after the manner of an ant, runs rapidly about 

 the tree. Before long it deliberately loosens its hold of the 

 branch, and, being very light, falls to the ground as gently 

 as a feather and receives no injury. " The peculiar instinct 

 which impels this newly hatched larva to thus precipitate 



