Orthoptera of North Carolina
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Neonemobius palustris (Blatchley, 1900) - Sphagnum Ground Cricket


Neonemobius palustrisNeonemobius palustrisNeonemobius palustrisNeonemobius palustris
Taxonomy
Family: Gryllidae Subfamily: Nemobiinae Tribe: PteronemobiiniSynonym: Nemobius palustris
Comments: One of six species in this genus that occur in North America north of Mexico (Cigliano et al., 2017), three of which have been recorded in North Carolina
Species Status: This species is believed to be closely related to Neonemobius cubensis and has been considered a subspecies of cubensis by Hebard (1934) and Fulton (1951). However, both SINA and OSF currently treat it as a separate species.
Identification
Field Guide Descriptions: Himmelman (2009)Online Photographs: SINA, BugGuide, Songs of Insects, Google Images,  iNaturalist, GBIFTechnical Description, Adults/Nymphs: Hebard (1913); Johnstone and Vickery (1970)SINA 524a.htm                                                                                  
Comments: The smallest of our ground crickets. Blatchley (1900) described it as pitch-brown in color over its entire body, although Hebard (1913) noted that some populations are a lighter clove brown and described Nemobius palustris aurantius as a southern form with ochraceous-rufus on the head and pronotum. Himmelman (2009) noted reddish-brown forms in the Northeast as well as some individuals that are yellowish-brown. Johnstone and Vickery (1970) attribute this range of colors to the isolation of individual populations of this micropterous species. Eunemobius cubensis is similar but is less solid brown, especially on its tegmina and abdomen (Hebard, 1913; Himmelman, 2009).
Total Length [body plus wings; excludes ovipositor]: 5.7 mm, NC males; 6.8 mm, NC females (Hebard, 1913)
Structural Features: Hebard (1913) and Johnstone and Vickery (1970) reported that no macropterous individuals have been found. Members of Neonemobius are distinguished by their small size. Females possess short, upwardly curved ovipositors, less than or equal to 2/3 the length of the hind femur, and that have fine teeth only on the dorsal side of the tip (SINA, 2017)
Singing Behavior: Fulton (1931) described the songs of palustris and cubensis as similar, consisting of trills of several seconds duration with pauses of similar lengths in between. In both species, the amplitude increases from the start to finish, with the trill ending abruptly. Although Fulton could not detect any differences in populations around Raleigh, the pitch of palustris is around 8.6 kHz at 78 F (= 25.5 C), compared to 7.5 kHz for cubensis at 80 F (SINA, 2017). Palustris also sings at a lower pulse rate, at about 42 pulses/sec at 78 F, vs. 55 pulses/sec for cubensis (SINA, accessed 2020).
Diagnostic Song Parameters:

Recording playback at normal speed.

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Distribution in North Carolina
County Map: Clicking on a county returns the records for the species in that county.
Neonemobius palustris
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: Blatchley (1900) described its habitat in northern Indiana as dense, damp patches of sphagnum moss within tamarack swamps and cranberry bogs. In North Carolina, our records appear to come primarily from areas where sandhill seeps or wet longleaf pine savannas are likely to be the main habitats. The habitat from the Wake County record is unknown, but forested seeps seem probable and may be used throughout most of the Piedmont and Low Mountains.
Diet: Stenophagous on Sphagnum species (Johnstone and Vickery, 1970). In North Carolina, Fulton (1931) reported that palustris did well in captivity feeding solely on Sphagnum, and its tight association with sphagnum bogs suggests a high degree of coevolution with these plants. However, like other crickets, it may also feed to some extent on other plants, small animals, and detritus.
Observation Methods: The song is high pitched and fairly weak, making it difficult for at least some people to detect in the field. However, individuals are reported to be easily flushed by pressing down on sphagnum mats, forcing large numbers out to the surface (Walker, cited by Blatchely, 1920).
Abundance/Frequency: Can be locally abundant. Blatchley (1900) and subsequent authors report dense populations associated with sphagnum bogs and swamps
Adult Phenology: Fulton (1931) reported that the earliest appearance of adults around Raleigh was August 12. The latest date he recorded (Fulton, 1951) is the end of October.
See also Habitat Account for Coastal Plain Herbaceous Peatlands
Status in North Carolina
Natural Heritage Program Status: [W3]
Natural Heritage Program Ranks: [GNR] [S1S2]
State Protection: Has no legal protection, although permits are required to collect it on state parks and other public lands
Comments: This species has one of the most restricted habitats of any of our orthoptera and its apparently limited dispersal abilities -- only micropterous individuals are known -- makes its occurrences highly isolated (see Johnstone and Vickery 1970) and probably highly vulnerable to the effects of habitat fragmentation. Prior to our documenting several populations in seeps in the Fall-line Sandhills, this species had not been recorded in the state since at least 1938.

Image Gallery for Neonemobius palustris - Sphagnum Ground Cricket

Neonemobius palustris Recorded by: Steve Hall and Bruce Sorrie
Richmond Co.
Comment: Individual 1. 42.2 syllables per sec @ 9.6 kHz. recorded in an extensive area of sphagnum located at the north end of a powerline that comes in from the south, intersecting the main powerline ROW
Neonemobius palustris Recorded by: Steve Hall and Bruce Sorrie
Richmond Co.
Comment: Individual 2. 44.2 syllables per sec @ 9.0 kHz. Recorded in an extensive area of sphagnum located at the north end of a powerline that comes in from the south, intersecting the main powerline ROW
Neonemobius palustris Recorded by: Steve Hall and Bruce Sorrie
Richmond Co.
Comment: Single individual recorded in a seep that had been recently bush-hogged. Sphagnum mats were extensive but mostly dried out and bleached white now
Neonemobius palustris Recorded by: Stephen Hall
Richmond Co.
Comment:
Neonemobius palustris Recorded by: Steve Hall
Richmond Co.
Comment: 38.8 syllables per second at 8.4 kHz
Neonemobius palustris Recorded by: Stephen Hall and Mark Basinger
Richmond Co.
Comment:
Neonemobius palustris Recorded by: Stephen Hall and Mark Basinger
Richmond Co.
Comment: Several flushed from a sphagnum mat
Neonemobius palustris Recorded by: Stephen Hall and Mark Basinger
Richmond Co.
Comment: Several flushed from a sphagnum mat
Neonemobius palustris Recorded by: Steve Hall and Bo Sullivan
Scotland Co.
Comment: At sphagnaceous edge of a streamhead pocosin; recorded along with Allonemobius fultoni. 35 pulses/sec at ~80 F