Laboulbeniales is an order of microscopic fungi within the class Laboulbeniomycetes that are obligate ectoparasites, primarily infecting insects and other arthropods. Unlike typical fungi, members of this order do not form mycelium; instead, they develop small, highly specialized thalli directly on the host’s exoskeleton. These fungi attach to specific body parts of their hosts, often exhibiting a high degree of host and site specificity. Reproduction is primarily sexual, with the formation of ascospores that can be transmitted between hosts through direct contact. Laboulbeniales are notable for their complex morphology despite their microscopic size and for their ecological role in influencing host behavior and population dynamics.