Orthoptera of North Carolina
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Anaxipha vernalis Walker & Funk, 2014 - Spring Trig

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Taxonomy
Family: Gryllidae Subfamily: Trigonidiinae Tribe: TrigonidiiniSynonym: Anaxipha n. sp. G
Comments: One of thirteen species in this genus that occur in North America north of Mexico (SINA, 2017); nine have been recorded in North Carolina. Vernalis belongs to the Delicatula Species Group, of which declicatula is the only other member.
Species Status: Treated as delicatula by Fulton (1951, 1956) based on genitalic features. Recognized as a separate species by Walker and Funk (2014). There are possibly two sibling species present, based on different song types produced in the spring and summer. However, these forms may represent different generations, as appears to be the case in a Neoconocephalus triops (see account page for that species).
Identification
Field Guide Descriptions: Online Photographs: SINA, Google Images,  iNaturalist, GBIFTechnical Description, Adults/Nymphs: Walker and Funk (2014)SINA 632a.htm                                                                                  
Comments: A very small, brown Trig. Unlike most members of the Exigua Group, it lacks a stripe on the lateral face of the femur (Walker and Funk, 2014). Structural features -- particularly the number of pegs on the stridulatory file -- must be examined to identify this species. This species is very similar in appearance and in genitalia to delicatula but they can be easily distinguished by their songs.
Total Length [body plus wings; excludes ovipositor]: 6.2-6.8 mm, males; 4.8-6.7 mm, females (Walker and Funk, 2014)
Structural Features: Stridulatory file with about 106 teeth (range 102-112). Ovipositor longer relative to hind femur, HF/OV < 3.1 (see Walker and Funk, 2014 for additional structural characteristics). Walker and Funk reported that no long-winged forms have been observed.
Singing Behavior: Songs consist of continuous trills, with the number of pulses per second ranging from 20 to 60 per second and the corresponding carrier frequencies (pitch) ranging from 3.5 to 6.5 (see graph below). Songs given in the spring last several minutes at at time, but later in the season songs are more often broken into segments that are 3-4 seconds in length, with gaps of up to 2 seconds separating them. They also differ in the relationship between pulse rate and dominant frequency (see graph below). During the spring, songs can be confused with those of Gryllus rubens, which has trills with similar pulse rates but with a much lower pitch. Although these differences are possible to pick out by ear, the use of spectrograms is recommended to distinguish these two species. Anaxipha exigua has a similar continuous trills but has a dominant frequency at 77 F of 7.2. Exigua also calls later in the season than vernalis, although there is a period of overlap in late July.
Graph of Songs:

Recording playback at normal speed.

Download Video: "MP4"

Nymphal Stages and Development: Apparently undescribed but unlikely to be distinguishable
Distribution in North Carolina
County Map: Clicking on a county returns the records for the species in that county.
Anaxipha vernalis
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: Fulton (1956) describes the habitat as primarily fresh-water marshes and stream borders, especially with thick herbaceous growth, including both Lizardtail and tall wetland graminoids. We also have records from floodplain forests more generally and from seepage slopes in the Sandhills.
Diet: Apparently unrecorded; possibly omnivorous
Observation Methods: Singing males are most easily detected both day and night. They may also be captured using sweep netting, although Walker and Funk (2014) state that this species is particularly difficult to capture.
Abundance/Frequency: Can be locally abundant; one chorus heard in Chapel Hill extended well over a half mile along a creek, with no gaps in singing males
Adult Phenology: Fulton (1956) gives the dates for adult vernalis (= delicatula) in the Piedmont of North Carolina as May 22 to July 21. We have, however, recorded them as early as April 6 in the Sandhills. We also have records -- possibly representing either a second brood or a different species -- from July to at least early August.
See also Habitat Account for General Sedge, Grass, and Rush Mires
Status in North Carolina
Natural Heritage Program Status:
Natural Heritage Program Ranks: [GNR] [S4?]
State Protection: Has no legal protection, although permits are required to collect it on state parks and other public lands
Comments: We currently have records for this species from just a small number of counties, with most of those being historic. However, it appears to occupy common types of habitats and is likely to be found throughout at least the Piedmont and probably the Coastal Plain.

Image Gallery for Anaxipha vernalis - Spring Trig

anaxipha vernalis Recorded by: Steve Hall
Chatham Co.
Comment: 		Anaxipha vernalis Recorded by: Steve Hall
Chatham Co.
Comment: Calling from Microstegium patches. 52 pulses per sec. @ 5.7 kHz
Anaxipha vernalis Recorded by: Steve Hall
Chatham Co.
Comment: ca. 40 pulses/sec @ 5.6 kHz and 72F; 8:30 am		Anaxipha vernalis Recorded by: Steve Hall
Durham Co.
Comment: 52 syllables per sec @ 5.6 kHz
Anaxipha vernalis Recorded by: Jim Petranka
Swain Co.
Comment: 43 syllables per sec @ 6.0 kHz and 74F 		Anaxipha vernalis Recorded by: Steve Hall
Orange Co.
Comment: 47 syllables per second @ 5.3 kHz
Anaxipha vernalis Recorded by: Ken Kneidel
Mecklenburg Co.
Comment: 42 syllables per sec. @ 5.7 kHz		Anaxipha vernalis Recorded by: Jim Petranka
Madison Co.
Comment: 40 pulses per second @ 5 kHz and air temp. ca. 75 degrees; Several adults were singing in or immediately adjacent to a marshy area dominated by Carex species. Individuals made a continuous trill for 20-25 seconds or more.
Anaxipha vernalis Recorded by: Steve Hall and Bo Sullivan
Richmond Co.
Comment: 60 syllables/sec @ 6.2 kHz and >80 F. Several males heard singing from the grassy margin of an old beaver impoundment. 		Anaxipha vernalis Recorded by: Steve Hall and Bo Sullivan
Scotland Co.
Comment: 50 syllables/sec @ 5.4 kHz and ~83 F. Several males heard singing from along a small grassy and shrubby seep;
Anaxipha vernalis Recorded by: Steve Hall
Orange Co.
Comment: 48 syllables per second @ 5.7 kHz. and 78 F; 09:52. Very few individuals are still calling		Anaxipha vernalis Recorded by: Steve Hall, Savannah Hall, Cordell Buckingham
Durham Co.
Comment: 43 syllables per sec @ 5.5 kHz and ~77 F; 20:00
Anaxipha vernalis Recorded by: Steve Hall
Orange Co.
Comment: 42 pulses per second at 5.3 kHz and 75 F. A large chorus has been singing for the past two days at this spot, despite somewhat flooded conditions

MP3 Gallery for Anaxipha vernalis - Spring Trig

1 Recorded by: Jim Petranka
Swain Co.
2021-07-08
Singing male was in vegetation along the banks of the Little Tennessee River; temperature 74 F; pulse rate ca. 40-45/sec. 		2 Recorded by: Ken Kneidel
Mecklenburg Co.
2021-06-13
Cattail marsh of roughly 3 acres bordered by extensive lizard tail. Calls were coming from weedy vegetation along the edge, not in the marsh. 42 pulses per second, 5.5 kHz, 79 F time 20:40.
3 Recorded by: Jim Petranka
Madison Co.
2021-05-31
Several adults were singing in -- or immediately adjacent to -- a marshy area dominated by Carex species. Air temp. ca. 75 degrees; 40 pulses per second; individuals made a continuous trill for 20-25 seconds or more; dominant frequency around 5 kZh.