Orthoptera of North Carolina
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View Gryllidae Members: NC Records

Neonemobius palustris (Blatchley, 1900) - Sphagnum Ground Cricket


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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 InsectsTechnical 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 apparently flightless 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 nd Vickery (1970) reported that no macropterous individuals have been found. Members of Neonemobius are distinguished by their small size -- males are less than 9 mm in body length. Females also 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).
Distribution in North Carolina
County Map: Clicking on a county returns the records for the species in that county.
Flight Dates:
 High Mountains (HM) ≥ 4,000 ft.
 Low Mountains (LM) < 4,000 ft.
 Piedmont (Pd)
 Coastal Plain (CP)

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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: Possibly stenophagous. 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.
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.
Status in North Carolina
Natural Heritage Program Status: [W3]
Natural Heritage Program Ranks: [GNR SU]
State Protection: Has no legal protection, although permits are required to collect it on state parks and other public lands
Comments: This species is one of the most habitat-specialized of any of our Orthoptera. Sphagnum-bogs and related habitats are also fairly narrowly distributed, and the apparent lack of flight in this species likely makes it highly vulnerable to the effects of habitat fragmentation. More needs to be known about its exact distribution and habitat requirements in the state in order to accurately assess its conservation status or to make specific recommendations about its management.