Orthoptera of North Carolina
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View Gryllidae Members: NC Records

Anaxipha exigua (Say, 1825) - Say's Trig


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Taxonomy
Family: Gryllidae Subfamily: Trigonidiinae Tribe: TrigonidiiniSynonym: Anaxipha pulicaria
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. Exigua belongs to the Exigua Species Group, which also includes tinnula, thomasi, tinnulacita, and tinnulenta in North Carolina (Walker and Funk, 2014).
Species Status: Fulton (1956) described three song types used by members of what was then considered Anaxipha exigua, one of which was later described as tinnulenta by Walker and Funk (2014)
Identification
Field Guide Descriptions: Elliot and Hershberger (2007); Himmelman (2009)Online Photographs: SINA, Songs of Insects, Google ImagesTechnical Description, Adults/Nymphs: Walker and Funk (2014)SINA 616a.htm                                                                                  
Comments: A very small, brown Trig. Like other members of the exigua group, it possess a broad dark 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; the song is also distinctive.
Total Length [body plus wings; excludes ovipositor]: 5.6-6.7 mm, males; 5.8-8.0 mm, females (Walker and Funk, 2014)
Structural Features: "Stridulatory file with about 117 teeth (range 100-135)" (see Walker and Funk, 2014 for additional structural characteristics). Macropterous individuals have been observed but are rare.
Singing Behavior: The song is a clear continuous trill with a pulse rate of about 44 pulses per second and the dominant pitch at 7.2 kHz (at 25°C) (Walker and Funk, 2014). Individual pulses are over-slurred and have a pure tonal quality like other members of this genus.
Recording playback at normal speed.

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Nymphal Stages and Development: Apparently undescribed but unlikely to be distinguishable, particularly from other members of the Exigua Species Groups
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: Fulton (1956) described the habitat of his trilling form of exigua (now recognized as true exigua) as consisting of deeply shaded mesic to wet forests, becoming most abundant in wet seeps dominated by Lizard Tail. Walker and Funk (2014), however, also include open woods and old fields in addition to riparian areas. They mention that exigua usually occurs in partial shade and is usually found near the ground to about 2 meters above it in coarse weeds or woody plants.
Diet: Apparently unrecorded; possibly omnivorous
Observation Methods: Singing males are most easily detected but they may also be captured using sweep netting
Abundance/Frequency: Records in North Carolina where numbers are given suggest that males are usually heard singly. Elliot and Hershberger (2007), on the other hand, report finding hundreds of individuals on single small trees.
Adult Phenology: Adults appear in late July and persist at least until mid October (Fulton, 1951)
Status in North Carolina
Natural Heritage Program Status:
Natural Heritage Program Ranks: GNR [S4S5]
State Protection: Has no legal protection, although permits are required to collect it on state parks and other public lands
Comments: This species has been recorded over a fairly wide area of the state and occupies fairly common types of habitats. Consequently, it is probably secure in the state.

Image Gallery for Anaxipha exigua - Say's Trig

Recorded by: Steve Hall
Durham Co.
Comment: 43 pulses per second @ 80 F (27 C); recorded near an oxbow pond in bottomland hardwood forest
Recorded by: Steve Hall
Iredell Co.
Comment: 42 pulses/sec at 9:16, 75 F
Recorded by: Steve Hall
Orange Co.
Comment: Singing from a sandy terrace along a creek. Temperature at 16:45 was 79 F (= 26 C); pulse rate was 38 pulses per second.
Recorded by: Steve Hall
New Hanover Co.
Comment: Pulse rate of 43 pulses per second at about 67 F (= 19 C). Calling from the edge of a marsh, possibly from the basal clump of a Scirpus