Orthoptera of North Carolina

Family (Alpha):

View	Gryllidae Members:	NC Records
Allonemobius walkeri Howard & Furth, 1986 - Walker's Ground Cricket

Taxonomy

Family: Gryllidae	Subfamily: Nemobiinae	Tribe: Pteronemobiini
Comments: One of ten species in this genus, all of which occur in North America north of Mexico (Cigliano et al., 2017). Eight species have been recorded in North Carolina.

Identification

Field Guide Descriptions:	Online Photographs: BugGuide, Google Images, iNaturalist, GBIF	Technical Description, Adults/Nymphs: Howard and Furth (1986)	SINA 529a.htm
Comments: A red-brown to blackish ground cricket (following Alexander and Thomas's description of allardi). The head is brown with two to three darker stripes, which are usually not contrasting, particularly at the rear of the head, but forming more distinct spots at the top. Differs in coloration and pattern from A. socius, which has pale, contrasting stripes on the back of the head, and from A. tinnulus, which has a more reddish head and pronotum. However, walkeri cannot be safely distinguished from A. fultoni and allardi based on photos and can only be identified based on specimens or by spectrogram (Howard and Furth, 1986).
Total Length [body plus wings; excludes ovipositor]: 9.9-11.7, males; 9.2-11.7, females (Howard and Furth, 1986)
Structural Features: Males have 183-208 stridulatory teeth, which is well above the range of fultoni and averaging lower than allardi, but overlapping in range (Howard and Furth, 1986). Walkeri is significantly larger than fultoni in all measurements, with a table listing these measurements presented by Howard and Furth.
Singing Behavior: The song of Allonemobius walkeri consists of a long, irregularly broken series of down-slurred syllables (see Hershberger, 2021; SINA), similar in shape to A. tinnulus, allardi, and fultoni. In Hershberger's Figure 6A, the syllables show an initial click (vertical bar) followed by a short over-slur and followed by a longer down-slur (see also examples in the Macaulay Library). According to Howard and Furth (1986), walkeri sings at a faster rate than allardi, producing 24-25 syllables per second at 23C (73F) compared to 13-16 for allardi (and still fewer for tinnulus); the dominant pitch ranges from 6.7 to 7.7 kHz. While they found no differences between walkeri and fultoni in terms of dominant pitch or rate of singing, the songs of fultoni are more regularly broken into segments separated by fairly fixed intervals of silence (fultoni also appears to differ in terms of habitats). Songs of Anaxipha thomasi are also similar, but the songs of that species have their highest pulse rates around 22-23 syllables per second with dominant frequencies around 8 kHz, whereas walkeri have their slowest pulse rates at about the same level, 21 syllables per second, but at a much lower pitch, around 7 kHz (compare song graphs). Thomasi, like other trigs, sings from vegetation rather than on the ground as in the ground crickets, and is strongly associated with stands of pine rather than the open herbaceous areas favored by walkeri.
Diagnostic Song Parameters:

Recording playback at normal speed.
Download Video: "MP4"

Distribution in North Carolina


County Map: Clicking on a county returns the records for the species in that county.


Adult Dates: High Mountains (HM) ≥ 4,000 ft. Low Mountains (LM) < 4,000 ft. Piedmont (Pd) Coastal Plain (CP) Click on graph to enlarge

Habitats and Life History

Habitats: According to Howard and Furth (1986), A. walkeri inhabits dry grassy fields and pastures, nearly always co-occurring with A. allardi, at least where their geographic ranges overlap. Records from North Carolina include an upland field dominated by Andropogon virginicus; a grassy powerline in a floodplain; an area of old field habitat also located in a floodplain; and a dry oak-hickory forest.

Diet: Probably omnivorous

Observation Methods: Most easily detected by its song

Abundance/Frequency: Usually heard as single indivduals

Adult Phenology: Adults emerge in late summer and fall; eggs overwinter (Howard and Furth, 1986)

See also Habitat Account for General Successional and Semi-Natural Grasslands

Status in North Carolina

Natural Heritage Program Status:

Natural Heritage Program Ranks: [GNR] S3S4

State Protection: Has no legal protection, although permits are required to collect it on state parks and other public lands

Comments: Although this species appears to be associated with common types of vegetation, walkeri was considered rare by Howard and Furth (1986) and by Hershberger (2021). Not enough is yet known about its distribution, abundance, and habitat preferences, however, to accurately assess its conservation status in North Carolina.

Image Gallery for Allonemobius walkeri - Walker's Ground Cricket
	Recorded by: Steve Hall, Dee Stuckey, and Savannah Hall Orange Co. Comment:	Recorded by: Steve Hall, Dee Stuckey, and Savannah Hall Orange Co. Comment: 27 syllables per sec @ 8.0 kHz; dry-mesic hardwood forest
	Recorded by: Stephen Hall Orange Co. Comment: Female found in the same area where males were recorded singing. Stripes are obscure at the back of the head but more visible on the top; head not as red as tinnulus	Recorded by: Steve Hall and Dee Stuckey Orange Co. Comment: 27 pulses/sec @ 8kHz and ~80 Fm 19:31. Singing from deep grass cover
	Recorded by: Steve Hall and Dee Stuckey Orange Co. Comment: 26 pulses per second @ 7.4 kHz, 71 degrees F (= 21 C); recorded in a powerline where tall old field forbs were growing next to a grassy path	Recorded by: Steve Hall Orange Co. Comment: 30 pulses per sec @ 7.9 kHz; 88 degrees F (31 C); recorded at the edge of a field maintained in broom sedges by mowing

MP3 Gallery for Allonemobius walkeri - Walker's Ground Cricket
1	Recorded by: Steve Hall, Dee Stuckey, and Savannah Hall Orange Co. 2024-08-24

Allonemobius walkeri Howard & Furth, 1986 - Walker's Ground Cricket

Image Gallery for Allonemobius walkeri - Walker's Ground Cricket

MP3 Gallery for Allonemobius walkeri - Walker's Ground Cricket