In Trichoptera there are at least four main types of external genitalia with corresponding complexes of internal structures: A - Ecnomid Type, B - Philopotamid Type, C - Rhyacophilid Type, and D - Integripalpian Type. The internal genitalic complex of caddisfly females is represented by the main structures: vagina, spermatheca with spermathecal sclerite, bursa copulatrix, median oviduct, and some additional ducts which connect these organs or serve other purposes: accessory gland duct, spermathecal duct, pre-spermathecal diverticulum (present only in Integripalpia and Rhyacophilidae and absent in all other Trichoptera and other insect orders), and spermathecal gland. The presence, development, position and morphology of internal genitalic structures are reliable marks for phylogenetic reconstruction; the shape and size of these structures, the configuration of spermatheca and its outer and inner microsculpture are also useful for high-taxa and even for species recognition.