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Montana Field Guides

Allard's Ground Cricket - Allonemobius allardi

Native Species

Global Rank: G5
State Rank: SNR


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General Description
The following is taken from Fulton (1931), Alexander and Thomas (1959), Vickery and Kevan (1985), Bland (2003), Capinera et al. (2004), and Himmelman (2009). This species was formally in the genus Nemobius. Body color of Allard’s Ground Cricket is dark brown to black without distinctive makings and covered with long sensory hairs which monitors their surroundings. The top of the head often has 3 faint longitudinal stripes, sometimes difficult to view. The anterior edge of the pronotum (thorax) is narrower than the posterior edge. Wings are shorter (bracyptrous) than abdomen, but long-winged (macropterous) forms do occur. There are long tibial spurs at the end of the hind tibia, one of which is chewed by the female and secretes a nuptial gift (see “Reproductive Characteristics” below).

Calling song description
The following is taken from Alexander and Thomas (1959), Fulton (1931 and 1933), Elliott and Hershberger (2007), Himmelman (2009), Morris and Morris (2004), and Walker's SINA website (2020). The Allard’s Ground Cricket, A. allardi, and the Striped Ground Cricket (A. fasciatus), are persistent singers both day and night. As in other crickets, the songs are produced only during the closing of the wings. The song of A. allardi has been described as a high-pitched continuous trill (some authors describing it as a “shrill tinkling quality continued for an indefinite period”) consisting of pulses (chirps) with a slight down-slur in frequency due to a wider spacing of the teeth at the middle end of the stridulatory vein, which results in an “ear-pleasing quality.” The pulse rate depends upon the ambient temperature. When singing, the male raises his wings (tegmina) about 45-degrees to the body, and spreads and vibrates them. Like most crickets, the right tegmen is the uppermost and the two tegmina are not identical. The right is darker in color and has a rougher surface. The left possesses a narrow-raised edge on the inner margin where it comes in contact with the stridulatory file of the right tegmen. There are two variations of the mating song.

Phenology
This species overwinters in the egg stage. Adults occur from late-July, reaching peak abundance from the middle of August to the middle of September, when they begin to decline, some lasting into early November. These are often the last singing insects to survive as adults into the late autumn, because they are protected from brief low temperatures by inhabiting deep grasses, crevices, burrows, under logs, boards, and stones (Alexander and Thomas 1959, Bland 2003, Vickery and Kevan 1985, and Howard and Furth 1986).

Diagnostic Characteristics
The following is taken from Fulton (1931), Alexander and Thomas (1959), Vickery and Kevan (1985), Bland (2003), Capinera et al. (2004), and Himmelman (2009). Body length in males is 7-11 mm, and females 8-12 mm. The stridulatory vein is always over 0.9 mm, more than two-fifths the width of the head behind the eyes. The number of teeth can vary from 165-200 with an average of 183 (this requires high magnification to see). The female ovipositor curves upward at a slight angle, the tip tapering and sub lanceolate bearing a row of evenly spaced saw-like teeth on the dorsal surface. The head in dorsal view is narrow and retracted into the pronotum. There are long tibial spurs at the end of the hind tibia, one which secretes a “nuptial gift” fluid chewed by the female (see “Reproductive Characteristics” below). The two hind tibial spurs are uneven, as occurs for Striped Ground Cricket (A. fasciatus) (refer to that species’ illustrations).

This species is easily confused for small Field Crickets, Gryllus spp., but the two Montana Allonemobius species are much smaller. However, they too are easily confused and difficult to identify because they do not possess any single morphological character by which they can be easily separated. They can be distinguished by using combinations of characters such as length of the female ovipositor, head banding intensity, and measuring the head width behind the eyes. Males of the species’ can be separated by measuring the length of the stridulatory vein and number of teeth on the file of the right tegmen viewed dorsally (compare “Diagnostic Characteristics” with the Striped Ground Cricket (A. fasciatus)) (Alexander and Thomas 1959).

Range Comments
The Allard's Ground Cricket ranges from the southeastern corner of British Columbia, angled southeastward through Montana, Wyoming, Colorado, to Alabama; then northeastward to Nova Scotia. In Montana, it has been reported in two counties (Vickery and Kevan 1985, Capinera et al. 2004, Walker's SINA website 2020).

Habitat
This species inhabits mostly dry, well drained woodland edges, upland fields and slopes, lawns, roadsides, and grassy sand areas (Alexander and Thomas 1959, Tennis 1983, Vickery and Kevan 1985, Bland 2003, and Himmelman 2009).

Food Habits
This is an omniverous species, consuming a wide range of herbaceous weeds, forbs, rust spores, moss, grass, legumes (such as alfalfa), and arthropods (Jacobs et al. 1992).

Reproductive Characteristics
Prior to mating, the male faces the female and sings, using one of its two special mating songs, and performs a dance by jerking his body backward and forward without changing the position of his feet. Male and female touch their antennae, performing what is called antennation. The male’s genitalia are protruded, but his spermatophore does not form until a short time before mating. The male turns away from the female, drops the tegmina, and backs toward the female and at the same time raises one hind femur with the tibia closed upon it, and moves it so far forward that it is inverted. The female crawls over the top of the male and begins to bite the specialized “gift-producing” proximal spine on the tibia. This brings the female forward for the male to push his claspers into the opening between her ovipositor and subgenital plate to attach the spermatophore. The pair remain in this position for 15-25 minutes, all the time the female biting the spine. When the female leaves, the spermatophore is attached with a tube through which sperm will be delivered to her spermatheca. Later she removes it and eats it. Ground Crickets, Allonemobius spp., produce one generation per year (Fulton 1931, Fedorka and Mousseau 2002, and Mays 1971).

References
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Citation for data on this website:
Allard's Ground Cricket — Allonemobius allardi.  Montana Field Guide.  .  Retrieved on , from