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 are one of the most common pests in and around homes in the north central states. Ants are social insects and are divided up into three castes: workers, males, and queens (figure 1). Workers are sterile, wingless females which range in size from 1/20 inch long to about 1/2 inch long.escription: Some species of carpenter ants are the largest ants in the north central states. They are black, or red and black; workers range in size from 3/16 to 1/2 inch. Colonies consist of major and minor workers.