The possible mechanisms for generation of genetic variability in a thelytokous form of the parasitic wasp, Aphytis mytilaspidis, were explored. Through cytological studies the thelytokous form was found to retain the meiotic divisions in egg maturation. Restoration of diploidy is achieved through the fusion of two sister nuclei of the second meiotic division (terminal fusion). Heterozygosity can be retained for such loci as undergo crossing over. Males are produced by the thelytokous form in a low frequency; both thelytokous males and females are sexually functional; and sexual processes occur in the thelytokous population.
