Orthoptera of North Carolina
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View Gryllidae Members: NC Records

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 ImagesTechnical 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 chirps -- 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 pulse trains, but with a slower within-chirp pulse rate of about 66 pulses 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 = chirp): "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."
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: We have no information on either the frequency of observations or abundance of this species in North Carolina
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 all historic. While it seems likely that the species still exists in the state, more surveys are needed to determine its current distribution and abundance.