Berosus affinis

A small (3.5 to 4.5 mm) water beetle. The elytra have a straw ground colour with a prominent pair of dark spots near the suture and additional spots nearer the apex. The black head, bulging eyes and broad dark patch on the pronotum are particularly noticeable. This dark pronotal patch may have a pale central line but this doesn't extend beyond half way. The elytral interstices are flat.

Berotus luridus is generally darker so the elytral spots are less noticeable.The dark pronotal patch has a pale median line that extends at least half way down. The elytral interstices (strips between the striae) are raised into ridges (flat in B. affinis).

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.

Ponds and other marshy habitat types.

All year round.

Widespread in the southern half of Britain but rather local.

Rarely recorded in Leicestershire and Rutland with only a handful of records.