Spores of the fungus enter the developing larva through the cuticle or orally with contaminated food. These spores germinate and the hyphae of the fungus invade the cells, killing the larva (usually after it has been capped over). Initially the dead larvae will be covered with a white cotton wool-like growth and may swell to fill the cell taking on its shape. After a time these will dry out and shrink to give the characteristic ‘mummies’ that are chalk-like at first turning to a greyish black colour as the fungal fruiting bodies develop. Worker bees uncap the cells of dead larvae so the mummies will be clearly visible; they will also be removed by the workers and may be seen in high numbers on the floorboard or at the entrance to the hive. In very heavily infected colonies, the workers will not be able to uncap all of the affected cells and if a comb is shaken the mummies may be heard rattling in the cells.