Honey Bee Parasites, Pests, Predators and Diseases

Sacbrood (prepupae in sack)

Larvae with sacbrood disease are easily removed intact from the cells, unlike those killed by American foulbrood. When removed and suspended from a toothpick or thin twig, the contents of the larvae are watery and the tough outer skin appears as a "sack" or bag of fluid which is filled with millions of sacbrood virus particles. The dried sacbrood scale lies flat, with the head end raised and darkened and the tail flat on the bottom side of the cell. The scales are rough and brittle and do not adhere tightly to the cell wall. Sacbrood usually disappears in the late spring when the honey flow has started. Strong colonies and regular requeening seem most effective in combating this disease. Since the disease is caused by a virus, no antibiotic is effective in preventing or controlling sacbrood.