The infected bees are hairless, thus they look smaller are black and shiny. Infested bees have splayed, shaky wings are often flightless. Weakened bees are pushed out of the hive by the healthy ones. Peak of infestation usually from late May to early July.
Robbery, inbreeding, metabolic disorders (pollen deficiency), strong forest habit, bacterial attack, infestation of viruses or fungi.
Measures to combat:
There are no remedies. Fighting the cause: stop robbery, take hives out of the forest habit.
Low remedy by feeding with a thin sugar solution or blossom honey.
Destroying dead bees (infestation by fungi or viruses can be contagious).