Symptoms of sacbrood are partially uncapped cells scattered about the frame or capped cells that remain sealed after others have emerged. Diseased individuals inside cells will have characteristically darkened heads which curl upward. The dead prepupa resembles a slipper inside the cell. Diseased prepupae fail to pupate and turn from pearl white to pale yellow to light brown and finally, dark brown. The skin is flaccid and the body watery. The dark brown individual becomes a wrinkled, brittle scale that is easily removed from the cells (unlike AFB).
Hairless Black Bee Syndrome (or Chronic Bee Paralysis)
Chronic bee paralysis is the only viral disease of adult bees that has a clearly defined symptom: an abnormal trembling motion of the wings and body. Other symptoms are the bees' inability to fly which forces them to crawl on the ground and up the stems of grass in front of the hive. The abdomens will be bloated and the wings will be partially spread or dislocated. Bees afflicted with the virus will appear shiny and greasy because of the lack of hair which should not be confused with robbing bees. Also, adult bees are chewed by other bees and harassed by guard bees at the entrance to the hive (again may be confused with signs of robbing). Adult bees die within a few days of the onset of symptoms. The virus is spread from bee to bee by unusually prolonged bodily contact or rubbing which causes many hairs or bristles to break exposing live tissue. Bees do not transmit sufficient virus to cause paralysis by food exchange because many millions of virus particles are required to cause paralysis when given to a bee in food. Bees vary genetically in susceptibility; therefore requeening is a good practice if symptoms appear.
Queenlessness can occur in many ways, but once a colony becomes queenless the reaction of the colony is predictable. The colony will become agitated and most of the activities of the hive are disrupted. When the beekeeper opens the hive, many bees will fan, much like when you see scenting bees (secretion of Nasonov pheromone and its dispersion by wing fanning). There may also be a loud roar from the bees. Usually within a few hours of being queenless, the bees will begin to construct emergency queen cells from existing cells containing worker larvae less than four days old. Nurse bees will supply the cell with large amounts of royal jelly to divert the development of the worker larva into a queen.
Usually the queen cell is constructed in time to permit requeening. If not, the colony becomes hopelessly queenless and will eventually die unless a new queen is added to rejuvenate the colony. During the time between queenlessness and complete colony collapse, workers will begin to lay eggs inside the cells. At first glance one would think there is a queen in the colony, but with a closer look, it is obviously laying workers. Workers have the ability to lay unfertilized eggs when their ovaries are stimulated. Worker ovary development is normally suppressed by the queen's presence, but if the queen is killed or if she is old and not producing adequate amounts of pheromone then the workers begin to produce queen cells or lay eggs. Differences between worker and queen eggs are undetectable to the naked eye. Laying workers are usually revealed by the manner in which they deposit their eggs. A queen will lay a single egg cemented to