Stonebrood is a rare fungal disease of honey bees caused by Aspergillus flavus that can kill bee larvae very quickly. Researchers experimentally infected bee larvae with the fungus and tracked how the disease progressed, finding that larvae died within 48 hours of infection. The study revealed that the fungus likely kills bees by producing toxins rather than by physical damage, and poses a health risk to beekeepers who inhale the fungal spores.