Arrhenotoky or arrhenotokous parthenogenesis is a form of parthenogenesis in which unfertilized eggs develop into haploid males.
This form is observed in some marine invertebrates, beetles, scorpions, mites, bees, etc.
For some invertebrates it is a form of sex determination: males are produced parthenogenetically, while diploid females are produced biparentally from fertilized eggs. In the case of the honeybee, the queen stores sperm and can lay both fertilized and unfertilized eggs. The unfertilized eggs developed into haploid drones by arrhenotoky.