Bladderwort flea beetle

Longitarsus nigerrimus (also known as bladderwort flea-beetle)[1] is a greenish-black coloured species of beetle in the tribe Alticini that can be found in European countries such Austria, Czech Republic, France, Germany, Great Britain, Hungary, Italy, Poland, Slovenia, Switzerland, Benelux, Yugoslavian states (except for Macedonia), Baltic states, Scandinavia, and in Eastern Europe (Belarus and Ukraine).

[2] It can also be found in North Russia, specifically in Siberia and east to Amur.

[3] The species emerge in midsummer to mate and lay eggs.

[1] They overwinter in Sphagnum moss, which can be found wet boggy areas.

When the moss goes underwater they use their front legs for breaststroke like movements to stay afloat.