THE GENETICS OF HABROBRACON JUGLANDIS ASHMEAD 



not extreme in the adult ani'iials stuliei pre- 

 sumably because extreme types did not survive 

 to the adult stage. Evidence of selective ac- 

 tion of mortality is shov/n by differences be- 

 tween frequency distribution curves of diploid 

 ■males and the curves of more viable types. 



In all material investigated (Grosch, 1945) 

 diploid male cell size was significantly larger 

 than female cell size. This is shown by the 

 number of microchaetae per unit area of wing 

 surface and by measurements of eye facets. To 

 explain diploid male mortality it is suggested 

 that doubled gene situations in the diploid 

 male, homozygous for a sex allele, might func- 

 tion poorly under the surface-volume relation- 

 ship of the large diploid male cell. The large 

 size of diploid male cells may itself be the 

 result of gene duplication. The system which 

 raises haploid male cells to a size comparable 

 with diploid female cells may be increased in 

 activity when its determiners are doubled in the 

 homozygous sex allele condition of the diploid 

 male. 



No statistically significant differences are 

 shown in body length between diploid males and 

 females, and observations indicate that diploid 

 males do not exhibit gigantism. Haploid male 

 mean body length is shown to be consistently 

 less than that of diploid wasps, and this is 

 taken as indication of the tendency toward dwarf- 

 ism of the haploid male. Wing length corre- 

 sponds to body length in all classes. 



Larger eyes of the male are a secondary sex 

 character not affected by cell size differences. 

 This sex character is not as clear cut as anten- 

 nal length. Long antennae of the male are a 



