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.
Ants. An estimated 20,000 species of ants exist in the world. All ants live in colonies and have a structured social system, with different castes-worker, soldier, queen and drone-all of which carry out specific tasks for the colony.Only the queen and the males she mates with on her maiden flight will reproduce.All the workers and soldiers are sterile females.ll ants live in colonies and have a structured social system, with different castes-worker, soldier, queen and drone-all of which carry out specific tasks for the colony. Only the queen and the males she mates with on her maiden flight will reproduce. All the workers and soldiers are sterile females.