3.8 to 4.8 mm. Black head and pronotum with dark red/brown elytra. The front corners of the elytra are a paler grey. It is generally covered in long, pale hairs.

Hydroporus species are generally very hard to separate but the size, black head, grey front to the elytra and overall hairiness make H. planus easier than most.

The rare H. marginatus is similar but has denser punctuation on the elytra and has wide, pale margins to the pronotum.

• c4mm
• very hairy
• dark head and pronotum
• paler (grey) front corners on the elytra

Unless identified by a recognised expert, a photo is required and the specimen should be examined with a microscope. In the comments box, state the key or ID method used and describe the size and identifying characters.

Usually found in temporary ponds and pools, even cattle troughs, but has also been recorded in running water.

Has been recorded in all months of the year, but peaking in June and October.

This species flies readily so often turns up in a wide variety of habitats.

Widespread and frequent in Britain.

Common in Leicestershire and Rutland.