258 ENTOMOLOGICAL SOCIETY 



" We shall begin with the moment when the fly places its ovi 

 positor 011 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 ovipositor 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 beforeit succeeds in getting it under the scales. It 

 does not succeed with buds in which the scales are closely im 

 bricated, 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 mak 

 ing a careful preparation 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 driven the 

 ovipositor into the centre of the bud, there comes a moment of 

 complete rest, and the fly sits motionless upon the bud. If it is 

 fixed in this position by dipping it into chloroform, nothing is 

 seen of the egg it still remains in the vagina. Then follows the 

 second part of the work, the pushing of the egg into the bud. 



" The egg slips, with its enclosed egg-body, to the base of the 

 ovipositor between the origin of the two spicuhe. The egg-body 

 glides over the point where the two spictilas embrace the tenon of 

 the seta, since the space remaining open between the two spiculas 

 is too small to admit it. But the egg-stalk, which follows, slips 

 between the two spiculae, is seized by them and driven forward ; 

 in this way the egg is pushed downwards into the ovipositor, 

 with the egg-body hanging out. 



"When at last the egg is about to enter the canal which has 

 been bored into the centre of the bud, it becomes evident that it 

 is impossible for the canal to admit the ovipositor and the egg- 

 body to pass in at the same time. The egg-body is always of 

 much greater diameter than the ovipositor ; on this account the 

 ovipositor is next partially withdrawn by the fly, until the pierced 

 canal becomes empty. The egg-body then enters the pierced 

 canal, and the ovipositor follows, pushing it before it. In short, 

 the whole forward motion is dependent on the egg-stalk being 

 propelled by the to-and-fro movements of the two spiculaB, and 

 the egg reaches the end of the bored canal, while the egg-stalk 

 remains lying within it." 



To sum the matter up, the operation according to Adler con 

 sists of three distinct stages: (i) the canal is first bored, after 

 which the fly rests ; (2) the egg is then passed from the ovarium 

 to the base of the ovipositor, the swollen end or body of the egg 

 hanging out, but being pushed along by means of the stalk be 

 hind being grasped between the two spiculge ; (3) finally, when 



