The Method of Ovipositing. 117 



or twenty minutes occupied by the laying of the ^^^'g, 

 a pricking fly could be fixed in position every successive 

 minute, the buds would yield us a long series of pre- 

 parations exhibiting the different stages in the birth of 

 an ^g%. Unfortunately this idea cannot be carried 

 out, on account of practical difficulties. In the first 

 place the time occupied in pricking the buds is not 

 always the same, and in the next each separate act is 

 itself of uncertain duration, since the fly has greater 

 obstacles to overcome in some cases than in others. 

 It is therefore only possible to learn to recognize some 

 of its different stages, and then from these to construct 

 the whole operation. 



We shall begin with the moment when the fly 

 places its ovipositor on the bud. She always chooses 

 the edge of one of the outer scales as a point of attack, 

 and pushes her ovipositor under it. Then the ovipo- 

 sitor glides under the scales to the base of the bud-axis. 

 Even this first act requires great strength on the 

 part of the fly. We sometimes see it attack the bud 

 repeatedly with its ovipositor, before it succeeds in 

 getting it under the scales. It does not succeed with 

 buds in which the scales are closely imbricated, hence 

 it always prefers buds with loose-lying scales. When 

 the ovipositor has arrived at the base, it is driven 

 towards the bud-axis so as to reach the rudimentary 

 leaves ; but the path made by the ovipositor is always 

 more or less curved. By making a careful prepara- 

 tion of any pricked bud, the canal can be plainly seen, 

 and the path taken by the ovipositor followed. After 

 the fly has finished the first part of its work, and 



