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.
Let's get the confusing bit out of the way first. Velvet ants are not really ants: they are wasps. They got their name because the females look like large ants, albeit ants clothed in dense velvety hairs of various hues: they can be yellow, orange, red, white or black. Female velvet ants have taken the idea of warning colouration to a whole new level.