Apr. lo, 1916 Oviposition of Megastigmus spermotrophus 67 



A spell of rainy weather persisted from May 8 to 25, and no further 

 records were secured. The subsidence of emergence after the latter date 

 made it impossible to obtain adults for liberating in the rearing cages, 

 and efforts to secure further records were not attempted. 



Difficulty was encountered in securing photographs, as females will not 

 oviposit if even slightly disturbed. If a cone was jarred in any way 

 while a female was in the act, the ovipositor would be withdrawn as rap- 

 idly as possible. Even though the ovipositor was inserted deep in the 

 cone the female would struggle to disengage it and fly away. However, 

 by raising the glass on the front of the cage it was possible to focus a 

 camera directly on the cones, and several pictures were obtained in this 

 way. For the purpose of further study and dissection, a number of females 

 were captured and killed with the ovipositor thrust into the cones. This 

 was best accomplished by quickly immersing the cone on which the female 

 rested in a graduate filled with chloroform. This killed the female so 

 quickly that her efforts to withdraw the ovipositor were seldom suc- 

 cessful. Several of the females which were killed in this position were 

 photographed (PI. VI, fig. i, 2). 



The time required for oviposition varies from two to five minutes. 

 The same female was observed to oviposit five times on the same cone, 

 and it is probable that the operation is repeated many times before the 

 egg-laying capacity is exhausted. The point selected for the insertion of 

 the ovipositor was always on the surface of a scale, never on a bract, 

 and may be either on the margin or near the center of the scale. The 

 female always assumed a position with head pointed toward the base of 

 the cone. As Douglas fir cones were pendent at the time of oviposition, 

 this allowed the female to stand with her head pointed upward (PI. V, 



%• 2, 3)- 



In cones which were dissected with the ovipositor of the female inserted 

 it was found that the ovipositor reached the seed in a few cases only. 

 Apparently where successful the ovipositor passes through the scale 

 nearest the surface and underlying bracts until it reaches the second or 

 third scale from the surface. It then follows down through the center 

 of the last scale nearly to its base and then turns forward into the seed 

 just ahead of it (PI. VII, fig. 2, 3). The fact that the ovipositor was 

 seldom found in the seed in the cones dissected is doubtless due to the 

 fact that the female partly withdrew her ovipositor in the death struggle. 



It would seem that successful oviposition occurs only when the egg is 

 deposited in the seed, as the larvae have never been found to work their 

 way through the tissues of the cone, and their development is confined 

 entirely to the interior of one seed. 



Numerous cases were found in which the ovipositor did not penetrate 

 even as far as the base of the scale. This occurred most frequently where 

 the cones were of such an age that the scales had hardened. In these 

 oases the tough tissues of the scales seem to bend the ovipositor out of 



