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.
Worker ants are sterile or non-reproductive female ants that tend the queen, the brood (eggs, larvae and pupae), and forage for food. Most species produce winged ants, called reproductives, during certain times of the year. These are male and female ants leaving the nest to mate and establish new colonies.ize of these castes of ants varies with species. Female reproductive Texas leafcutting ants can have bodies about 20 mm in length. Harvester ant workers range from 5 to 9 mm and reddish brown to yellow or black, while red imported fire ants workers range from 1.5 to 4 mm and reddish brown with a darker abdomen.