Bees that emerge after being parasitized by a single female and her offspring have a shorter life span than do nonparasitized bees. Bees parasitized by more than two mites may die before emerging, or if they do emerge, they weigh less, may appear deformed and seldom leave the colony. The number of bees in the colony diminishes steadily as the number of mites increases. Less nurse bees are produced to feed the brood, and brood production ceases. At this stage, the entire colony collapses. All remaining adults usually leave the colony at one time, with each bee carrying numerous mites. These heavily infested bees often fly into nearby colonies and transfer mites in the process.
The total collapse of a colony usually comes as a complete shock to the beekeeper. One day the colony appears “strong” (many bees), and two weeks later, the colony is dead, without a single live bee present.
Mites can be dispersed quickly whenever infested bees come in contact with uninfested ones. This can happen easily when infested bees (especially drones) drift (enter a colony that is not their own) into an uninfested colony, or during robbing, as uninfested bees remove honey from a colony occupied by infested bees.
-John Skinner, University of Tennessee
Bee Informed Partnership