OBSERVATIONS ON THE SPERMATOGENESIS OF THE 

 GALL-FLY, DRYOPHANTA ERINACEI (MAYR). 



H. L. WIEMAN. 

 Zoological Laboratory, University of Cincinnati. 



Introduction. 



Dryophanta erinacei is one of the gall-producing Hymenoptera 

 having two generations in the year: males and females in the 

 spring, and females alone in the fall. The fertilized, eggs of the 

 bisexual generation produce females exclusively, while the un- 

 fertilized eggs of the female generation produce both males and 

 females. 



The material for this study was obtained on April 13, 1914, 

 from galls occurring on white oak trees (Quercus alba) in the 

 neighborhood of Cincinnati. The galls are smooth spherical 

 protuberances on the bud-scales, several millimeters in diameter. 

 Usually one, but occasionally two, and sometimes three galls 

 very close together are found at the end of a single twig. Twigs 

 bearing galls were cut off, brought into the laboratory, and the 

 cut ends inserted in sand moistened with water. Ten days later 

 males and females emerged from the galls, and continued emerg- 

 ing for two weeks. Copulation took place immediately after 

 emergence. 



These galls supplied all stages of developing males and females 

 from the late larva to the imago. For fixation Petrunkewitsch's 

 fluid was used; penetration being facilitated by making a longi- 

 tudinal incision through the body wall. In some cases ovaries 

 and testes were dissected out, but better results were obtained 

 when the organs were left in situ and the entire animal sectioned.^ 



Embedding was done in rubber-parafhn, and serial sections cut 

 10 /J. in thickness. Two methods of staining were used: safranin 

 and light-green, and iron-haematoxylin with or without counter- 

 stain. After dehydration the stained sections were cleared and 



' For assistance in collecting and preserving material I wish to acknowledge my 

 indebtedness to Dr. Annette F. Braun. 



34 



