This family of microsporidia has oval or elliptical spores of one type only with an external cell wall, not a pansporoblastic membrane or cyst wall. The spores contain a sporoplasm, a coiled polar tube and a polar capsule.
The species infect a variety of organisms, including insects, both pest and beneficial species. This page deals only with species infecting insect pests. For species infecting beneficial insects like honey bees see the section on Microsporidia (of beneficial insects).
The following genera are currently entered under Nosematidae: