Pteronemobius heydenii - Marsh-cricket
(Fischer, 1853)

Description: A small cricket (♂ 5-6 mm, ♀ 5-7 mm), colour is dark brown and black. Head without light markings. There are 4 spines on the outer side of the hind tibiae. The wings extend at least halfway up the abdomen. The ovipositor is short (2 mm) in relation to the bodylength.
Similar species: Nemobius sylvestris
Adults: from May to August
Song:
Pleasant, high-pitched chirp, lasting 1 to 4 seconds and increasing in volume. There is a 1-2 second pause between two chirps. It sings both in daytime and at night.

Source: Orthopteres de France, © Roesti (field recording, 23 °C)
Habitat:  Humid and warm habitats. It's difficult to catch the animals, best recording method is listening to the song.
Distribution:
Its distribution is not well known but most probably it is a scarce species.

Pteronemobius heydenii, male
(Author: N. Moulin, source: INPN.fr, CC BY NC SA)

Pteronemobius heydenii, female
(Author: Gintautas Steiblys, source: biodiversity-georgia.net)