48 N. H. AGR. EXPERIMENT STATION. [Bulletin 171 



had emerged in late summer, and ascribed to a second brood. 

 It has already been suggested, in the discussion of the number of 

 broods, that these flies may have represented accelerated develop- 

 ment, rather than a normal second brood. If this were the case 

 it would not be surprising to find that these females were sexually 

 comparatively immature. The fact that the dissections cited 

 showed a period of this length appears to the writer additional 

 indication that this may have been the case. 



PROCESS OF EGG-LAYING. 



The manner of egg-laying was carefully studied and described 

 by Harvey (25, p. 209). It was again observed and described 

 by Illingworth (34, p. 142). Our observations of the process 

 do not differ from those cited, except in the average length of 

 time required, which probably would vary with the time of day 

 and temperature, and the activity of the fly. 



At first the fly runs around over the surface of the fruit as 

 if searching for a place to its liking. Sometimes it turns around 

 several times. The thorax is then turned downward, the sharp 

 ovipositor extruded, and the point thrust through the skin of 

 the apple. The ovipositor is worked up and down, rapidly at 

 first and then slowly. After the egg is placed the fly walks away, 

 then stops and cleans the ovipositor with the hind legs. 



The entire process, from beginning to end, was sometimes com- 

 pleted in approximately one minute, but usually occupied from 

 two to four minutes, and in one instance the total time occupied, 

 including the preliminary trials and the cleaning of the ovipositor, 

 was seven minutes and forty-two seconds. 



The egg-puncture is roughly circular in outline, and at first 

 is decidedly inconspicuous, but later is readily distinguishable 

 with the naked eye. 



The egg is deposited slightly beneath the skin of the fruit, 

 somewhat at an angle rather than vertically, and with the pedicel 

 end toward the surface of the fruit. 



CHOICE OF VARIETIES FOR EGG-LAYING. 



Although many experiments were carried out in which apples 

 of diverse varieties were made available for egg-laying to flies 



