The Fall Field Cricket (Gryllus pennsylvanicus) is one of ten species of Gryllus crickets known from the eastern United States (at least twice that many, mostly undescribed as of 2004, are known from the western states). The Fall Field Cricket is among the several eastern U.S. Gryllus species found in pastures, lawns, and other open areas. The songs of the Fall Field Cricket, Spring Field Cricket (G. veletis), and Sand Field Cricket (G. firmus) are all loud, clear chirps delivered at a rate of 1 to 3 per second. Field crickets sing both day and night, but are typically quiet at dawn.
Fall Field Crickets are large, shiny black, and round-headed. The tegmina range from light brown to black. Females of the generally larger Sand Field Cricket have an ovipositor whose length tends to exceed body length whereas the ovipositor in the Fall and Spring Field Crickets is generally shorter than the body. Fall and Spring Field Crickets are nearly identical in appearance.
The Fall and Spring Field Crickets each have a single generation annually, but they overwinter in different stages. The Spring Field Cricket overwinters as a mid-sized juvenile and matures in spring. Its adults are dying out by the time Fall Field Crickets, which overwinter in the egg stage, begins to mature and call. The rich chirping of Fall and Spring Field Crickets is a familiar and seemingly ubiquitous sound across their wide range (and, through movies, beyond). Noticing the period between the demise of most of the Spring Field Crickets and the maturation of significant numbers of Fall Field Crickets at a particular location has been described as "like catching an eclipse of sound" (Himmelman 2009). In the northeastern U.S., the Spring Field Cricket reaches maturity from April into July; Fall Field Crickets are found as adults from August through early frost (adults of both species may be present from late July to early August).
The Fall Field Cricket probably ranges over most of the United States except for most of the southeastern coastal plain. Both Spring and Fall Field Crickets are found in a wide variety of habitats and are common around buildings, where they hide in cracks and crevices, under rocks, or in shallow burrows. As winter approaches, field crickets are attracted to warmth and often find their way into houses and other buildings.
(Capinera et al. 2004; Elliott and Hershberger 2007)
Although R.D. Alexander and R.S. Bigelow, mid- 20th century pioneers of the study of the behavior and diversity of crickets and katydids, developed the appealing hypothesis that the Fall and Spring Field Crickets diverged from a common ancestor by "allochronic speciation", i.e., through a divergence of overwintering stage (Bigelow 1958; Alexander and Bigelow 1960; Alexander 1968), subsequent molecular phylogenetic studies have indicated that these two species are not in fact each other's closest relatives, making this hypothesis untenable (Harrison and Bogdanowicz 1995; Huang et al. 2000).
Gryllus pennsylvanicus and G. veletis cannot be reliably distinguished by either song or external morphology (although in some localities the ovipositors of G. pennsylvanicus average substantially longer than those of G. veletis). However, G. veletis overwinters as mid-to-late instar juveniles, whereas G. pennsylvanicus overwinters in the egg stage. Both species have only one generation per year. Consequently, G. pennsylvanicus adults are most abundant in fall and G. veletis adults are most abundant in spring. In all localities where the species have been studied, a few adults of the two species occur together in midsummer.
More information: subfamily Gryllinae, genus Gryllus
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Gryllus pennsylvanicus is known as the fall field cricket. G. pennsylvanicus is common in southern Ontario, is widespread across much of North America[3][4] and can be found even into parts of northern Mexico. It tends to be absent in most of the southwestern United States including southern California. Within its geographic range this field cricket will burrow into soil in fields and forest edges.[5] Individuals inhabit grassy disturbed areas [4][6] and are often found around areas of human habitation.[7]
Adults reach 15–25 millimetres (0.6–1.0 in) and coloration ranges from dark black to dark brown, although some specimens show a slight reddish tint.[8] The black antennae tend to be longer than the body span of the species. The cerci are longer than the head and prothorax, and the wings do not extend past the cerci.[9]
During the breeding season, the number of adult female G. pennsylvanicus captured in pitfall traps peaks approximately two weeks after the peak in the number of adult males captured,[10] which seems to indicate protandry. Breeding in some areas also coincides with the seed rain from certain agricultural weeds,[11] possibly providing females with food resources to increase their fecundity. Males call from the mouths of burrows or cracks in the ground into which they escape when scared. Calling males are separated from each other by approximately 7.7 to 10.3 m in the field,[12] likely making it costly for females to sample large numbers of potential mates. Male G. pennsylvanicus calling song consists of short chirps – roughly two to three per second – each consisting of three to five pulses (each a single closure of the male forewings or tegmina).[13][14]
Like most other gryllines, females are attracted to male calling song [15][16][17] and are attracted to higher calling effort at least when population density is low.[18] In an elegant series of field experiments, Zuk [19] showed that female G. pennsylvanicus were more attracted to calling song produced by older males than that of younger males. Males found paired with females in the field were also older than unpaired calling males nearby.[20] However, in the earlier experiment higher calling effort explained a small, but statistically significant proportion of the variance in female attraction,[19] raising the possibility that the apparent preference of females for the songs of older males might be due to differences in calling effort between older and younger males.
Adults are mostly active during night when the males sing to attract females.[15] Females will then lay their eggs by injecting their ovipositor into soil. A single female will lay around 50 eggs at a time and can lay well over 400 eggs in her life span. Eggs laid in the late summer and fall seasons will overwinter and hatch the following spring.[13][21] There is one generation per year.[13] Sometimes as winter approaches adults will find their way into houses where they will try to overwinter.
Because the only reliable method of distinguishing G. pennsylvanicus and G. veletis is based on the timing of their life history,[13] Alexander and Bigelow [21] proposed that G. veletis and G. pennsylvanicus were sister species and had diverged through a process of allochronic speciation, whereby a temporal separation between the breeding seasons of the two incipient species restricts gene flow.[21] However, G. veletis and G. pennsylvanicus are not sister taxa; instead, G. pennsylvanicus form a well-supported clade with G. ovisopis and G. firmus,[22][23] the latter of which forms an extensive hybrid zone with G. pennsylvanicus in the eastern United States.[24] Currently, a major molecular phylogenetic revision of North American Gryllinae is underway (D. Gray, pers. comm.) that will include the approximately 20 [4] western species as well as eastern species left out of earlier phylogenies (e.g. G. vernalis). This greatly anticipated work will undoubtedly provide ample diversity fodder for research into the evolution of life histories.
G. pennsylvanicus is an omnivorous [25] organism and has been shown to be a significant predator of both seeds [10][11][26] and invertebrates.[27][28][29] The broad diet of G. pennsylvanicus, coupled with seasonal variation in the availability of different types of prey (plant or animal) could exert substantial diversifying selection on cricket life histories (i.e. the genotypes that are optimal in high seed abundance years are likely different from those that are most fit in years of high invertebrate prey – genotype by environment interactions [30]).
Recorded food plants of G. pennsylvanicus include smooth crabgrass (Digitaria ischaemum), lamb's quarters (Chenopodium album), English plantain (Plantago lanceolata), switchgrass (Panicum virgatum), common ragweed (Ambrosia artemisiifolia) and chicory (Cichorium intybus). Even though they are a sizable cricket for North America they are preyed upon by everything from hawks to hornets.
A female fall field cricket, Gryllus pennsylvanicus
A male fall field cricket, Gryllus pennsylvanicus
A nymphal male fall field cricket, Gryllus pennsylvanicus
A pair of fall field crickets, Gryllus pennsylvanicus, mating
Gryllus pennsylvanicus is known as the fall field cricket. G. pennsylvanicus is common in southern Ontario, is widespread across much of North America and can be found even into parts of northern Mexico. It tends to be absent in most of the southwestern United States including southern California. Within its geographic range this field cricket will burrow into soil in fields and forest edges. Individuals inhabit grassy disturbed areas and are often found around areas of human habitation.
Gryllus pennsylvanicus is een rechtvleugelig insect uit de familie krekels (Gryllidae). De wetenschappelijke naam van deze soort is voor het eerst geldig gepubliceerd in 1838 door Burmeister.
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