Diseases of Honey Bees
Sacbrood (sealed cells with punctures and affected larvae)
Both worker and drone larvae can be infected by sacbrood. Death usually occurs after the cell is sealed and the larva has spun its cocoon. Pupae may be killed occasionally, but adult bees are immune to the disease. Dead brood often is scattered among healthy brood. The cappings over dead brood are first punctured and the affected brood is later removed by the bees. The larvae gradually change from pearly white to dull yellow or gray, and finally to black. The head of the larva, the first part of the body to change color, becomes black. Larvae die in a stretched-out position with their heads raised.