Moths of North Carolina
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10 NC Records

Neargyractis slossonalis (Dyar, 1906) - Dimorphic Leafcutter Moth

Taxonomy
Superfamily: Pyraloidea Family: CrambidaeSubfamily: AcentropinaeTribe: ArgyractiniP3 Number: 800747.00 MONA Number: 4769.00
Identification
Field Guide Descriptions: Online Resources: MPG, BugGuide, iNaturalist, Google, BAMONA, GBIF, BOLDTechnical Description, Adults: Dyar (1906)Technical Description, Immature Stages: Habeck (1988)                                                                                 
Adult Markings: The following is based in part on the description by Dyar (1906). The head, thorax and antennae are brown, while the most distinctive feature on the forewing is a very broad sub-basal band at about one-third the wing length that is whitish with varying degrees of brownish dusting. The band is margined with a narrow, dark brown line on both sides and adjoins a brown, triangular patch at the wing base. The apical margin adjoins a region with a white ground color that is overlain with varying degrees of dark brown dusting. In some specimens this region may be organized as a broad brownish band. The apical third of the forewing has a narrow, oblique, whitish costal streak at about two thirds that extends inward to near the middle and projects towards the tornus. This is followed by a dark brown or orangish-brown subterminal costa blotch, then a second whitish costal streak that also project towards the tornus. The apical margin has a narrow orangish band that is margined inwardly with a thin line of dark brown scales.

The hindwing has a dark brown basal patch and a broad, whitish, sub-basal band with brownish dusting that matches similar marks on the forewing. One or two orangish blotches with blackish margins often adjoin the band apically, and a light yellowish to orangish blotch is often present at the tornus. The apical half of the hindwing has a broad whitish region that is peppered with blackish specks and a series of terminal black spots that are separated by metallic scales and set in a faintly orange terminal area.

Neargyractis slossonalis general resembles certain other crambids with complex wing markings and terminal black spots on the hindwing (e.g., Petrophila canadensis; Eoparargyractis irroratalis), but can be readily separated by the broad, sub-basal band on the forewing and hindwing.
Forewing Length: 6-7 mm (Munroe, 1972).
Adult Structural Features: Munroe (1972) has descriptions of the male and female genitalia.
Adult ID Requirements: Identifiable from good quality photos of unworn specimens.
Immatures and Development: The larval life history is rather poorly documented, with our knowledge based almost entirely on Habeck’s (1988) observations in Florida. The author found the gilled larvae in both running and standing water habitats such as streams, rivers, lakes, and roadside ditches. Most of the specimens were found within clusters of submerged living roots, including those of grapes, ashes, and cypresses that grew along stream banks. They were also found among the roots of Water Hyacinth in ditches and lakes. The larvae fed on young, white roots and tended to avoid older, brown roots. They were surmised to also possibly feed on the associated periphyton. Pupation occurred in a cocoon that was spun among the roots, and portions of the roots were incorporated into the cocoon. Habeck (1988) noted that the larvae were present year-round in Florida, and that the adults were often seen resting on vegetation along the banks of streams and rivers.

The larvae have a creamy pale to light brown body that is densely covered with minute spinules. The head is dark brown with cream-pale areas, and the prothoracic shield varies from yellowish-brown to dark brown. The final instars reach a maximum length of around 20 mm.
Larvae ID Requirements: Identifiable from close inspection of specimens or by DNA analysis.
Distribution in North Carolina
Distribution: Neargyractis slossonalis is mostly restricted to the southeastern US. The range extends from southeastern Massachusetts southward along the Atlantic Coast states to southern Florida, and westward along the Florida Panhandle to southern Alabama. Populations have been found in western Kentucky that appear to be geographic isolates. As of 2023, we have only a few records that are restricted to the southern Coastal Plain, including the Sandhills.
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)

Click on graph to enlarge
Flight Comments: The adults fly year-round in Florida and mostly from May through September farther north. As of 2023, our records extends from early May to early September.
Habitats and Life History
Habitats: Local populations are generally associated with streams, rivers, lakes, and other habitats that provide food and shelter for the aquatic larvae.
Larval Host Plants: The larvae subsists on the young, submerged roots of vascular plants that grow along the banks of river and streams or in standing water habitats such as flooded ditches and lakes. Habeck (1988) found the larvae feeding on the roots of wild grapes (Vitis sp.), Ashes (Fraxinus), Cypresses (Taxodium) and Common Water-hyacinth (Oshuna (= Eichhornia) crassipes). - View
Observation Methods: The adults are attracted to lights. Information is needed on the habitats and food plants that are used in North Carolina.
Wikipedia
Status in North Carolina
Natural Heritage Program Status:
Natural Heritage Program Ranks: GNR [S2-S3]
State Protection:
Comments: This species appears to be uncommon within the state, but more information is needed on its distribution and abundance before we can accurately assess its conservation status.

 Photo Gallery for Neargyractis slossonalis - Dimorphic Leafcutter Moth

Photos: 5

Recorded by: Mark Shields on 2021-07-04
Onslow Co.
Comment: 		Recorded by: Mark Shields on 2021-07-04
Onslow Co.
Comment:
Recorded by: Jim Petranka, Bo Sullivan and Steve Hall on 2021-06-09
Richmond Co.
Comment: 		Recorded by: Jim Petranka, Bo Sullivan and Steve Hall on 2021-06-09
Richmond Co.
Comment:
Recorded by: Hunter Phillips on 2021-05-05
Onslow Co.
Comment: