''Gryllus firmus'', commonly known as the sand field cricket, is a species of

cricket Cricket is a bat-and-ball game played between two teams of eleven players on a field at the centre of which is a pitch with a wicket at each end, each comprising two bails balanced on three stumps. The batting side scores runs by str ...

in the subfamily

Gryllinae Gryllinae, or field crickets, are a subfamily of insects in the order Orthoptera and the family Gryllidae. They hatch in spring, and the young crickets (called nymphs) eat and grow rapidly. They shed their skin (molt) eight or more times before ...

. It is found in the southeastern United States.

Description

''Gryllus firmus'' is very similar in appearance to other crickets found in the southeastern United States, the southeastern field cricket (''Gryllus rubens'') and the Texas field cricket (''Gryllus texensis''). It has a black head and

prothorax The prothorax is the foremost of the three segments in the thorax of an insect, and bears the first pair of legs. Its principal sclerites (exoskeletal plates) are the pronotum ( dorsal), the prosternum ( ventral), and the propleuron ( lateral) o ...

, and a brown abdomen. It can be distinguished from these two species by the coloration and venation of the forewing, but more particularly, by its call. Males of this species chirp while males of the other two species trill.

Distribution and habitat

''Gryllus firmus'' occurs in the coastal plain of the southeastern United States. Its range extends from

Connecticut Connecticut () is the southernmost state in the New England region of the Northeastern United States. It is bordered by Rhode Island to the east, Massachusetts to the north, New York to the west, and Long Island Sound to the south. Its capita ...

and New Hampshire to Florida and

Texas Texas (, ; Spanish: ''Texas'', ''Tejas'') is a state in the South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2020, it is the second-largest U.S. state by ...

. The long winged morph is migratory.Bioscience. The Evolution and Genetics of Migration in Insects
/ref> It is replaced to the north and west of its range by the fall field cricket (''Gryllus pennsylvanicus''), and the two species hybridise to a limited extent where their ranges overlap. Its typical habitat is grassland, pasture, roadside verges and lawns on light, free-draining sandy soils.

Biology

''Gryllus firmus'' exhibits wing polymorphism; some individuals have fully functional, long hind wings and others have short wings and cannot fly. Females of the latter morph have smaller flight muscles, greater ovarian development and produce more eggs, so the polymorphism adapts the cricket for either dispersal or reproduction. In some long-winged individuals, the flight muscles deteriorate during adulthood and the insect's reproductive capabilities improve. ''G. firmus'' is unusual among field crickets in laying a mixture of two types of egg. Some eggs develop immediately and take two to four weeks to hatch, while others have a

diapause In animal dormancy, diapause is the delay in development in response to regular and recurring periods of adverse environmental conditions.Tauber, M.J., Tauber, C.A., Masaki, S. (1986) ''Seasonal Adaptations of Insects''. Oxford University Press I ...

, with delayed hatching taking place after from five to twenty-eight weeks. Individual females lay both egg types, with the proportion of the quick-developing types varying from 50% to 95%. Researchers hypothesize that this reproductive strategy is particularly appropriate for ''G. firmus'' because of the variability in the temperature and the soil moisture content in the sandy, fast-drying soils in which it lives. Unpredictable droughts are less likely to cause population collapses when the risk is spread in this way.

References

{{Taxonbar, from=Q10509532 firmus Orthoptera of North America Insects of the United States Insects described in 1902 Taxa named by Samuel Hubbard Scudder