The offspring of the virgin females are in most of these instances females; but among the bees and wasps parthenogenesis occurs normally and always results in the development of males, the " queen " insect laying either a fertilized or unfertilized egg at will.
Wagner made his classical observations on the production of larvae from unfertilized eggs developed in the precociouslyformed ovaries of a larval gall-midge (Cecidomyid), and subsequent observers have confirmed his results by studies on insects of the same family and of the related Chironomidae.
There are species of gall-fly in which males are unknown, the unfertilized eggs always developing into females.
These unfertilized eggs develop directly, often in the uterus.
In Dictyota the unfertilized oosphere is found to be capable of undergoing a limited number of divisions, but the body thus formed appears to atrophy sooner or later.