What is "hydraenidae"

Hydraenidae is a family of very small aquatic 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.

The larvae, although preferring damp habitats near water, are non-aquatic and tend to drown easily.