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.
Carpenter ants are usually larger than most other house-infesting ants. They vary in color from a dull black or reddish yellow color to a combination of black and dull red or reddish orange. Worker ants range in size from 5/16 to 7/16 inches long. Carpenter ants tunnel into wood to form nest galleries.