Orthoptera of North Carolina
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Anaxipha delicatula (Scudder, 1878) - Chirping Trig

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Taxonomy
Family: Gryllidae Subfamily: Trigonidiinae Tribe: Trigonidiini
Comments: One of thirteen species in this genus that occur in North America north of Mexico (SINA, 2017); nine of which have been recorded in North Carolina. Delicatula is part of the Delicatula Species Group, which also includes A. vernalis.
Species Status: Fulton (1951, 1956) treated both vernalis and delicatula under the name delicatula. In splitting the two into separate species, Walker and Funk (2014) assigned all of Fulton's records for delicatula to vernalis, except for one series from Carolina Beach.
Identification
Field Guide Descriptions: Online Photographs: SINA, Google Images,  iNaturalist, GBIFTechnical Description, Adults/Nymphs: Walker and Funk (2014)SINA 618a.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 73 teeth (range 66-77); ovipositor 1.3-1.6 mm, ratio of length of hind femur to ovipositor 3.0-3.3. Long-winged forms can be common at lights.
Singing Behavior: Songs consist of series of nearly regular short trills, rather than the continuous trills characteristic of vernalis. The within-chirp pulse rate is about 79 pulses per second at 77 F (= 25°C), with the dominant frequency at 5.7 kHz. Anaxipha litarena -- which is found in the same tidewater areas at about the same season -- also has songs consisting of short trills, but with a slower pulse rate of about 66 syllables per sec at 77 F (25° C), but with a very similar dominant frequency at 5.9 kHz. Walker and Funk further distinguish these two species by characteristics of the pulse train (PT = trill): "in delicatula the PT rate is nearly always faster, the PT durations are usually shorter, and the PT intervals are relatively longer." They note, however, that "in Florida the PT phrasing seems always to be useful in separating the two species by ear but this may not be the case in coastal North Carolina." One specimen we recorded at Atlantic Beach had a pulse rate that fits delicatula (based on the graph given in Figure 7 of Walker and Funk) but had relatively long trill durations and relatively short inter-trill intervals, both of which are a better match to litarena. Based on its association with a Spartina marsh, however, we have assigned it to delicatula.
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.
Adult 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: Occurs with tinnula in "in cordgrass marshes of coastal NC" (Walker and Funk, 2014); they also occur in "fresh water marshes, including lizardtail (Saururus) and cattails (Typha); on herbaceous undergrowth in riparian areas."
Diet: Apparently unrecorded; possibly omnivorous
Observation Methods: Singing males are most easily detected but they may also be captured using sweep netting
Abundance/Frequency:
Adult Phenology: Walker and Funk (2014) give dates between June and September for populations north of Florida
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 reaches the northern extent of its range in North Carolina and except possibly for the specimens from Corolla, our few records are mostly historic and one recent record is somewhat questionable in terms of its song characteristics. More surveys are needed to determine its current distribution and abundance.

Image Gallery for Anaxipha delicatula - Chirping Trig

Recorded by: Steve Hall and Dee Stuckey
Carteret Co.
Comment: 3 individuals heard singing in a Spartina marsh. 36 syllables per sec @ 60 F.

MP3 Gallery for Anaxipha delicatula - Chirping Trig

1 Recorded by: Steve Hall and Dee Stuckey
Carteret Co.
2024-10-27
Recorded at 10:15 pm at about 60 F. 36 syllables per sec at 4.0 kHz.