Synonyms and other taxonomic changes
Gryllus Linnaeus, 1758
A very difficult genus, because most species are extremely similar in appearance and in morphology. In a given area, it is usually possible to learn the various species through experience, by learning which songs go with which crickets at what time of year. However, from photographs and even with pinned specimens it is very difficult if not impossible to identify many individuals with certainty. A few species are distinctive enough to recognize on sight, but most are not. This is a group where it is actually usually easier to identify a specimen by hearing it than by seeing it! Another complication is the fact that several species (especially in the west) do not even have names yet. And yet another complication is that females do not sing.
Knowing when and where a specimen is found is helpful (and in some areas there are only one or two species), but having a recording of the song as well is better.
It should be stressed here that identifications made here will often be tentative, since without being able to examine specimens in hand, and without hearing male songs, it is not always possible to be absolutely certain which species is shown in a photograph. So, specimens posted to a given species should be considered as "probably" correct, but some may be wrong (even if they look correct).
New: A 2019 paper by David B. Weissman & David A. Gray presents the results of a decades-long study of Gryllus north of Mexico that doubled the number of known species and greatly increases what was known of the previously recognized species
Some useful regional treatments of Field Crickets are listed below, but there additional species occuring in other regions that are not treated in either one, and species may look different in other regions from their descriptions in these works. Theses publications can be helpful in other regions, but it should be remembered that the further from the region covered, the less accurate and comprehensive they will become. Also, new species are being named that may not be covered.
Weissman, D. B., & Gray, D. A. (2019). Crickets of the genus Gryllus in the United States (Orthoptera: Gryllidae: Gryllinae). Zootaxa, 4705(1), 1-277.
Singing Insects of North America
has photographs and information about Field Crickets (and their relatives), plus sample songs of many species.