Newly described aquatic insects, belonging to the genus Hydropsyche, are helping close substantial knowledge gaps regarding the biodiversity of Azerbaijan, Iran, and Türkiye. Caddisflies (order Trichoptera) are vital components of freshwater ecosystems, and the Hydropsyche genus is among the most diverse and ecologically important, comprising more than 8% of all Trichoptera species recorded in the Western Palearctic region.