48 BULI^ETIN 126. 



effort that had been made for her comfort, the female began 

 laying eggs within fifteen minutes after she entered the cage. 

 Evidently the insect sometimes begins egg-laying very soon after 

 it emerges, for the female just mentioned had not been out of the 

 cocoon more than two hours ; we did not see the pairing of the 

 sexes, and it may not have taken place, for as we shall see later, 

 the female will sometimes lay unfertilized eggs. 



In laying an egg, the female takes a position on the shoot a 

 few inches from its tip, with her head towards the tip, and quickly 

 works her long, curved, saw-like ovipositor into the shoot. At 

 figure b, plate III, this ovipositor is shown much enlarged and 

 drawn out in position for egg-laying ; when not in use it is drawn 

 upward and rests nearly out of sight in a groove in the end of the 

 abdomen. This ovipositor is pushed or sawed in its whole 

 length, and the egg is then quickly forced along between the two 

 blades of the ovipositor and is deposited in the pith of the shoot, 

 as shovi^n much enlarged at d, plate IV. The ovipositor is 

 quickly withdrawn, and the whole operation of laying an ^^'g is 

 accomplished in about a minute. 



The &<g% is of an elongate-oval shape, of a yellowish-white color 

 when first laid, about a millimeter (1-25 of an inch) in length, 

 of a delicate structure, and without any characteristic sculpturing. 

 In a day or two after deposition, transparent areas appear at both 

 ends of the ^^z, and before hatching the whole ^gg loses its 

 whitish opaque appearance and becomes transparent so that the 

 developing grub can be plainly seen inside. 



The slit cut by the ovipositor when an egg is laid is so small 

 that it can scarcely be found even with a hand-lens until about 

 two days after it is made. By that time nature, in her efforts to 

 heal the wound has caused an increased growth around the slit, 

 and there is thus a slight elevation on the shoot at that point. 

 The egg-slit is readily seen on the lower part of the enlarged 

 shoot shown at c on plate IV. Most of the eggs are doubtless 

 laid in the latter half of May ; some are not laid until June, as we 

 received several on June 8th that had been laid only a few days. 



How and why the shoot is girdled. — Immediately after the opera- 

 tion of laying an egg in the pith of the shoot is finished, the 

 ■female walks up the shoot for from one-half an inch to an inch 



