The BVD stands for Back Vertex Distance, this is a measurement that is included on any prescription where the sphere or cylinder powers are higher than + or - 5.00D and to a lesser extent some prescriptions where it is less than this power.
Winged Drone | Alate | Male Ant. Drones are the only male ants in a colony. They are born from un-fertilized eggs. Drones are not like typical ants. They donât do any work in their nests, and they look more like wasps than ants. They are reproductive winged ants and so are alates.
Known as workers or soldiers, female ants care for the eggs, tend to the larva, build and repair the nest, forage for food, and protect the colony. Male ants develop from unfertilized eggs. Also called drones, male ants have wings and are fertile to mate with the queen. Male ants are much smaller than females and have longer antennae.