Jamaican field cricket
Gryllus assimilis (Fabricius 1775)

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20 s of calling song [1.78MB]; male from Dade County, FL; 24.5°C. (WTL483-16)
6 s of calling song [259KB]; same as above but truncated and down-sampled.
23 s of mixed courtship [1.89MB]; from Dade County, FL; 24.5°C. (WTL483-16mc)

spectrogram
Sound spectrogram of 2 s of calling at 24.5°C (from WTL483-16). Dominant frequency 3.6 kHz.
Click on spectrogram to hear graphed song.

The song of this species is distinctive. Each chirp has six to ten pulses, with the initial ones being briefer and more rapidly delivered than the terminal ones. All pulses come too fast to be easily heard as separate sounds, and the chirp rate is unusually slow—about one chirp per second. G. assimilis is also distinctive morphologically. It has short brownish pubescence on the pronotum, the areas around the compound eyes are light yellow-brown, and the lateral arms of the epicranial suture are easily seen. All individuals are long-winged (Walker and Sivinski 1986).

From 1915 until 1957, the many species of North American Gryllus were generally classified as Gryllus assimilis or Acheta assimilis, because until songs were used to distinguish species, taxonomists could not agree on what groups of Gryllus specimens deserved species status. The real G. assimilis was described from Jamaica and is known in the United States only from southern Florida and Brownsville, Texas.

Note:  Until 2009, southern California populations of a related species (Gryllus multipulsator) were considered to be Jamaican field crickets, but their calling songs are distinctive, with more pulses per chirp and a higher dominant frequency.

Life cycle:   No diapausing stage, which has facilitated continuous rearing for scientific purposes.

More information:  subfamily Gryllinae, genus Gryllus

References:  Bigelow 1958, Alexander & Walker 1962, Weissman, Walker & Gray 2009.

Nomenclature:  OSF (Orthoptera Species File Online)