Hydraenidae

Hydraenidae is a family of very small aquatic beetles, sometimes called 'minute moss beetles', with a worldwide distribution. These beetles are generally 1–3 mm in length (although some species reach 7 mm) with clubbed antennae. They do not swim well and are generally found crawling in marginal vegetation. Most are phytophagous but a few saprophagous and predatory species are known.