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.
Noting Physical Characteristics. 1  1. Look at the color. Carpenter ants are usually brown or black. 2  2. Note size. As you observe ants, try estimate their size. 3  3. Watch for a round thorax. The thorax refers to the segment of an ant just below its head.  4. Look at the antenna and waist.