Honey Bee Diagnostic Services
Causative Agent: Virus
- This disease is more often a problem in the spring or after a substantial loss of workers.
- Larvae are infected and die on their backs with the head slightly elevated.
- The internal structures of the larva break down however the exoskeleton remains uncompromised making it a “sack” of sorts.
- Progression of color: white? yellow? brown ? dark brown.
- Cadavers if not removed by the workers deflate uniformly, dry into a dark “scale”. Unlike American Foulbrood the scale is not adhered to the cell and can be easily removed.
- Consistency of dead brood is watery and granular inside the tough leathery “sack”
- Sacbrood is most common a few weeks after a colony looses a high number of the adult workers due to pesticides or other causes. If a cause can be identified, steps should be taken to avoid it reoccurring in the future.
- Weak colonies can be reinforced with additional workers, a new queen, or improved environmental conditions
Odor is not a reliable method of distinguishing this disease
Irregular brood pattern can be a sign of a problem (but not necessarily Sacbrood)
Other Useful Sites:
Information and Pictures of American, European and Sac brood Diseases
Mid-Atlantic Apiculture Research & Extension Consortium Disease Control
Root, A. I. (1990) The ABC & XYZ of bee culture 40 th ed. A.I Root Co. Medina, OH.
Morse, R.A. & R. Nowogrodzki (eds). 1990. Honey bee pests, predators and diseases . Cornell University Press Ithaca , NY .
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