Chalkbrood disease in "M. rotundata," specifically larvae, was discovered in 1974 in Nevada. This disease occurs from exposure of "M. rotundata" to "Ascosphaera aggregata", which is introduced into the nest cells through nectar and pollen provisions that females bring back from foraging visits"." Signs of chalkbrood infection have been observed to occur in the fifth instar larva, leading to the milky appearance of the larval hemolymph and development of a pink, tan, or gray cast in the head or abdominal region. These changes are accompanied by the spread of pink, tan, or gray color throughout the body of the larva and dark-colored, fungal cysts appear under the cuticle.