sex-determination system haplodiploid sex-determination system https://en.wikipedia.org/wiki/Haplodiploidy https://www.wikidata.org/wiki/Q1098692 A sex-determination system in which males develop from unfertilized eggs and are haploid, and females develop from fertilized eggs and are diploid. Haplodiploidy determines the sex in all members of the insect orders Hymenoptera (bees, ants, and wasps) and Thysanoptera ('thrips'). The system also occurs sporadically in some spider mites, Hemiptera, Coleoptera (bark beetles), and rotifers. arrhenotoky haplodiploidy