Global freshwater habitats can be categorized in many ways. Based on characteristics of their hydroperiod, they can be arranged on a continuum from Permanent, through Intermittent, to Episodic.The insect communities found across these habitats might also be expected to form a continuum. Habitats that dry for only short periods support largely facultative, permanent-water species. Those that remain dry for much longer periods contain obligate species highly adapted and restricted to temporary waters. Lentic intermittent waters contain a subset of the major taxa found in permanent ponds and lakes, although the species differ. Lotic intermittent waters have a subset of the entomofauna found in permanent streams, but develop a lentic subset (especially Coleoptera and Hemiptera) as they dry out. Episodic waters tend to be dominated by dipterans, typically the nematoceran families Culicidae, Chironomidae, Ceratopogonidae, Psychodidae, and Tipulidae.