The possibility of within host competition of several pathogens was investigated in larval honey bees (Apis mellifera L.). Previous studies have examined the development and effects of pathogens on honey bees, however little is known on the possible competition among pathogens within the host. In this study we investigated in vitro development and progress of concurrent infections of several fungal species including Ascosphaera apis (Ascomycota), a common pathogens in honey bee larvae and a causative agent of chalkbrood disease, and an opportunistic fungus of the genus Aspergillus, the causal agent of a rare stonebrood disease.