Two uncommon species, Hydrellia tarsata Haliday and H. flaviceps Meigen, are recorded for the first time from Russia and from its north-western part, respectively. Larval habitats, host plants (Stratiotes aloides L.) and braconid parasitoids of both the species are indicated for the first time. H. tarsata is shown to develop abundantly within the lake littoral zone. The braconid Chaenusa opaca Stelfox is recorded from Russia for the first time.