10-11-2015 MONTE CORONA - SOUTHERN FIELD CRICKET (Gryllus bimaculatus)

Gryllus bimaculatus is a species of cricket in the subfamily Gryllinae. Most commonly known as the two-spotted cricket, it has also been called the "African" or "Mediterranean field cricket", although its recorded distribution also includes much of Asia, including China and Indochina through to Borneo. It can be discriminated from other Gryllus species by the two dot-like marks on the base of its wings.

The species is popular for use as a food source for insectivorous animals like spiders and reptiles kept as pets or in zoos. They are easy to raise and do not require prolonged exposure to cold in order to complete their life cycle.

In the wild, male crickets do not tolerate one another and will fight until there is a winner. The loser usually retreats without serious injury. The fighting method involves opening the mandibles as wide as possible, gripping the opponent's mandibles and pushing with the hind legs.

Male crickets of this species produce several distinctive chirps, though each sound is made by rubbing the two outer wings together. Loud and steady chirps made throughout the night are to attract females and to warn off other males. Loud fast-frequency chirps are emitted when males encounter one another and are preparing to fight. They are intended to frighten off the rival male. There are two other chirp patterns that can be observed in their mating behaviors. A soft clipping sound, 'calling' song, is made when a female is known to be nearby but in a certain distance, and more rigorous sound, 'courtship' song, is made when a female is close enough to mate (mounting on the male's back). These two songs can be easily distinguished by human ears based on its chirp patterns and frequency components.

Whether cricket song pattern (e.g. frequency spectrum) reflect song-emitter's body size is controversial. A recent study failed to detect body-size effect on both calling and courtship songs of G. bimaculatus.