THE HYLOTOMA. 1^1 



twig or stem, which it hkcs, and immediately the insect clasps 

 it with its legs, bends the back, and places its head low. Then 

 the saw suddenly appears under the end of the body, and is dug- 

 deeply into the green stem like a knife. Immediately the skin 

 of the twig is pierced, the laminae which form the double saw 

 are stretched slightly apart, and the gentle saw-like motion cuts, 

 deeper and deeper. Each saw cuts so as to separate from its 

 fellow, and to Aviden the slit, whilst the rough parts of the 

 outside of the saws scrape and enlarge the wound also. In a 

 few seconds or minutes the slit has become large enough for the 

 purpose of the saw-fly, and when this time has arrived the insect 

 rests perfectly still for a short period, and the saws separate 

 sideways and enlarge the slit; at the same time an o.^^ passes 

 down between them slowly but surely. The o.^^ is laid at the 

 bottom of the slit in safety, but more has to be done to ensure 

 the future comfort of the larva and its freedom from danger. If 

 the Q^^ were simply left at the bottom of the wound the vegetable 

 fibrous cells would soon close over and effectually imprison it 

 for ever, and the young larva would be crushed before it was born, 

 or starved. Every care is taken, however, to prevent this mis- 

 fortune. The Q.^^ is hardly laid before a mucus secretion, provided 

 by special glandular structures, escapes from the insect, and enters 

 the wound and covers its sides ; it acts as an irritant to the 

 plant, and soon makes itself felt by the vegetable tissues, which 

 it alters and indurates in a remarkable manner. No sooner is 

 it deposited than the fibres become wider apart, and soon blacken, 

 whilst the deeper-seated tissues become thickened and impaired, 

 so far as their groAving poAvers are concerned. The ^^^ thus 

 remains free at the bottom of the slit, and does not suffer from 

 the groAvth of the surrounding tissues, thanks to the glandular 

 secretion. 



Egg after (i^^ is deposited in the same manner, and Avith the 

 same precautions, and Ave may often distinguish the tAvigs Avhere 

 all this has gone on, and Avhich contain a long series of eggs in 

 separate slits. Sometimes only three or four Abounds may be 

 counted, but ten or fifteen or more punctures are often made. 

 The operation of laying is by no means easy, and it requires 

 much care ; so the female only deposits a fcAV eggs CA'cry day, 



