Gryllus integer

Scudder, 1901

Western Trilling Cricket

Gryllus integer, the western trilling , is a field cricket distinguished by its nearly continuous trilling song rather than discrete chirps. It occurs in the western United States, where males produce species-specific calling songs to attract females. The species has been extensively studied for its behavioral , including alternative mating tactics, personality traits, and antipredator responses. show geographic variation in song structure, with some California males producing chirped songs rather than continuous trills.

Pronunciation

How to pronounce Gryllus integer: /ˈɡrɪləs ˈɪntɛɡər/

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Identification

Distinguished from other Gryllus field crickets primarily by song: produces a rapid, nearly continuous trill rather than discrete chirps. Some California produce fast chirps with 2–3 syllables per chirp and ~30 ms pauses; Arizona populations use exclusively 2-syllable chirps. Morphologically similar to other black-headed Gryllus ; definitive identification requires acoustic analysis or geographic context. Larger than some at 17–24 mm.

Appearance

Medium to large field cricket, 17.1–24.0 mm in length. (fully winged). and pronotum jet black; tegmina (forewings) light brown.

Habitat

Occupies ground-level microhabitats in disturbed open areas. Found in cracks and burrows in soil, particularly along roadsides, near buildings, and around human habitation. Males preferentially call from warmer microsites, and microhabitat temperature selection influences calling .

Distribution

Western United States. Documented from Oregon, California, Arizona, New Mexico, and Texas.

Seasonality

Active during warmer months; calling activity occurs from evening through night, peaking 2–6 hours after sunset. Males call less near sunrise, possibly in response to reduced fly activity. stage not explicitly documented for this , though related field crickets overwinter as or nymphs.

Life Cycle

Hemimetabolous development with , nymph, and stages. Nymphs undergo multiple (eight or more in related ) before reaching adulthood. Specific details of G. integer timing not documented in available sources.

Behavior

Males employ two alternative mating tactics: calling (stationary singing to attract females) and searching (active movement to locate females). Tactic use varies with . Males fight aggressively for access to females, with heavier, sexually mature males showing greater aggression. Calling song attracts females but also the fly Ormia ochracea, creating a trade-off between mate attraction and risk. Anti- includes 'freezing' (immobility), which shows -level variation in suggesting genetic or maternal effects. Boldness (measured as hiding behavior) is repeatable during ontogeny; juveniles are generally bolder than adults. Fast-growing individuals mature earlier and invest less in immune defense than slower-growing conspecifics.

Ecological Role

Prey for diverse including spiders, reptiles, rodents, bats, and birds. for flies Ormia ochracea and Exoristoides johnsoni. Males serve as acoustic signalers in , with their songs exploited by phonotactic parasitoids.

Human Relevance

Occasionally enters human dwellings. Used as food source for captive insectivorous animals. Subject of extensive behavioral and ecological research. Chirp rate varies with temperature, though the continuous trill of typical makes this less applicable than for chirping .

Similar Taxa

Gryllus pennsylvanicusEastern fall field cricket with discrete chirping song; distribution (eastern vs. western North America) and different song structure distinguish them.
Gryllus veletisSpring field cricket; differs in seasonality and geographic range, with discrete chirping song rather than continuous trill.

More Details

Song Variation

Geographic variation in song structure is pronounced. Most produce continuous trills, but Davis, California males produce fast chirps with 2–3 syllables per chirp. Arizona populations use exclusively 2-syllable chirps. Californian females prefer 2-syllable chirps over 3-syllable ones and show preference for chirp pauses of 24–36 ms.

Parasitoid Pressure

Ormia ochracea, a tachinid fly, locates males by phonotaxis to calling song, depositing larvae that consume the . This imposes significant selection on male calling and may explain reduced calling near sunrise when fly activity is lower.

Personality and Life History

Research demonstrates pace-of-life : bold juveniles tend to have lower immune responses later in life, and fast-growing individuals mature early with reduced immune investment compared to slow-growing conspecifics.