Family Hydrachnidae Leach, 1815

This is a rather homogenous, monotypic family. Larvae of the genus Hydrachna Müller, 1776 parasitize aquatic beetles and bugs (Davids 1973, Biesiadka & Cichocka 1994, Zawal 2003); adults were observed feeding on insect eggs (e.g. Stevens & Greven 1999), sucking from macrophyte tissues was also reported (Davids et al. 2007, Olom- ski pers. comm.). The family has a rather isolated position within Hydrachnidia, due to their unique mouth part morphology and oviposition behaviour (females provided with an ovipositor, oviposition in plant tissues–Böttger 1972).