Gryllus bimaculatus De Geer, 1773

Gryllus bimaculatus De Geer, 1773

Figs 142 View Figure 142 , 143 View Figure 143

References for Socotra.

Burr 1903: 412, 422 [as Liogryllus bimaculatus ]; Wranik 2003: 315–316, plates 147, 149.

Diagnostic notes.

Gryllus bimaculatus is a large pitch-black cricket with yellow markings at the base of the long tegmina. Its size and colouration make it an unmistakable species.

Distribution and occurrence.

Gryllus bimaculatus is a widespread species in southern Europe, northern and eastern Africa and parts of Asia. It is known to swarm and cross large distances, also across open seas ( Ragge 1972).

Only one ancient record (1899) is known from the island, while recent ones are numerous (Fig. 142 View Figure 142 ). It could mean that the island has been colonised several times, with only the recent one being successful. In 2010, it was common in Ayhaft and Adho Dimello.

Habitat and biology.

All kinds of habitats and vegetation types. Records from 20–1450 m a. s. l. The species is attracted by light (Adho Dimello, 30 Oct 2010).

Bioacoustics.

The calling song of Gryllus bimaculatus is an echeme, lasting about 100 ms and repeated at about 4–5 per second (Fig. 143 View Figure 143 ; https://xeno-canto.org/877943). Echemes consist of three (rarely two) syllables of more or less equal duration and loudness. The carrier frequency of the song is around 4.7–4.8 kHz and has many harmonics at higher frequencies.