Dead off-color larvae usually have a fluffy, cotton-like appearance. Mummified larvae may be mottled with brown or black spots, especially on the undersides. Larvae that have been dead for a long time may become completely black. Desiccated mummies are shrunken, hard, and resemble small pieces of chalk. May rattle in comb when shaken. May be especially evident during spring but then may disappear with improving environmental conditions.
Chalkbrood is a fungal brood disease of honey bees caused by the spore-forming fungus Ascophaera apis. Dead larvae are chalky white and usually covered with fungus filaments (mycelia) that have a fluffy, cotton-like appearance. Mummified larvae may be mottled with brown or black spots, especially on the undersides, from the presence of maturing fungal fruiting bodies when the fungus sporulates. Larvae that have been dead for a long time may become completely black as fruiting bodies fully mature. Desiccated larvae may have a yellow-grayish color with a “nipple” appearance when viewed within the cell and may rattle when the comb is shaken. The larvae remain shrunken and hard, resembling small pieces of chalk. They usually do not have a distinctive odor.
Chalkbrood may be especially evident during spring but then may disappear with improving environmental conditions. Since chalkbrood is an inheritable characteristic, requeeningrequeen:
to replace a queen; old queens are often removed and replaced by a ripe queen cell or by a mated queen via an introduction cage
colonies may help reduce its presence. Feed colonies if chalkbrood is observed in spring, avoid using pollen traps on colonies with chalkbrood.
Snyder R. 2020. Chalkbrood disease primer. BeeInformed. Accessed 2023. https://beeinformed.org/2020/11/09/chalkbrood-disease-primer/
Shimanuki H and Knox D. 2000. Diagnosis of Honey Bee Diseases. US Department of Agriculture Agriculture Handbook 690. https://www.ars.usda.gov/is/np/honeybeediseases/honeybeediseases.pdf
MAAREC. 2005. Bee diseases & their control. Mid-Atlantic Apicultural Research & Extension Consortium Publication 4.9. https://canr.udel.edu/maarec/wp-content/uploads/sites/18/2010/03/Diseases_of_Honey_Bees_PM.pdf
Sanford MT, Jack CJ, and Ellis J. 2019. Chalkbrood recommendations. University of Florida/IFAS Extension. Accessed 2023. https://edis.ifas.ufl.edu/publication/AA138
USDA Logan ARS Bee Lab. 2018. Chalkbrood: A disease of bees. USDA Agricultural Research Service. Accessed 2023. https://www.ars.usda.gov/pacific-west-area/logan-ut/pollinating-insect-biology-management-systematics-research/docs/chalkbrood/
