Moths of North Carolina
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2 NC Records

Bellura gortynoides Walker, 1865 - White-tailed Diver Moth


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Taxonomy
Superfamily: Noctuoidea Family: NoctuidaeSubfamily: NoctuinaeTribe: ArzaminiP3 Number: 932513.00 MONA Number: 9523.00
Identification
Field Guide Descriptions: Covell (1984)Online Photographs: MPG, BugGuide, iNaturalist, Google, BAMONA, GBIF, BOLD                                                                                 
Adult Markings: The ground color of the forewings is yellow to buff and lacks the pale and dark shadings found in the obliqua-densa group (Forbes, 1954). The postmedian is deeply scalloped, with the scallops deeper than wide and accented on the veins.
Wingspan: 40-48 mm (Forbes, 1954)
Adult Structural Features: The front is flat in this species, compared to the bulging frons found in the obliqua-densa group (Forbes, 1954). The antennae of the female is simple versus the pectinate antennae found in obliqua and densa.
Adult ID Requirements: Identifiable from good quality photos of unworn specimens.
Immatures and Development: The following life history account is based on that of Center et al. (2002) and Eiseman (2022). The larvae specialize on Broadleaf Pond-lily (Nuphar advena). The females lay a clutch of around 400 eggs in early summer, with the eggs deposited in small clusters on either leaf surface. A cluster can contain up to 20 eggs, with the eggs covered with hairlike scales from the tip of the female’s abdomen. The hatchlings emerge in about 5-6 days and burrow into the leaves, then mine the leaf blades during the first three larval stages. Larvae commonly feed gregariously at first, with as many as eight in a single mine, but they are typically solitary by the end of the second instar. Mines vary in shape and can be more or less linear, digitate, or blotch-like. They are at first whitish, but the upper and lower epidermis soon turn brown and begin to disintegrate.

After the larvae attain a diameter larger than the thickness of the leaf blade, they begin to burrow into the petiole, either directly or via the midrib. The petiole tunnels extend below the waterline, with the larvae often feeding with their head below the water but with the tail above. Two large spiracles near the end of the abdomen provide for respiration while the larva is submersed in this fashion. The larva routinely backs up the tunnel to breathe and to expel frass through the entrance hole. With time the tunnels may reach 60 cm in length and extend nearly to the rootstalk. On cool, damp evenings, larvae may emerge and feed on the leaf surface, scraping the upper epidermis or occasionally eating the leaf margin. They may also move to new plants, so that not all petiole burrows are associated with leaf mines.

The larval period lasts 44–47 days at 24 C and there are six or seven instars. The last instars can reach 41 mm in length, and have an orange head and a dark brown cervical shield with a white medial line. The body is olive brown with dark bands at the posterior end of each segment. The fully grown larvae pupate within the petiole burrow. The dark brown pupa floats suspended within the burrow, with its head and thorax above water and oriented toward the surface. The adults emerge in about 9 days for a total laboratory developmental period (egg to adult) of about 60 days (Center et al., 2002).

This wide-ranging species can vary from being univoltine to multivoltine depending on the latitude. In Indiana, the first generation larvae pupate within the petioles and the adults emerging in midsummer. Larvae in the second brood are borers, but between September and November they swim to shore and overwinter under bark or in leaf litter, with pupation occurring in the spring. Farther north, populations are univoltine and the larvae overwintering on the shore (Eiseman, 2022).
Distribution in North Carolina
Distribution:
County Map: Clicking on a county returns the records for the species in that county.
Flight Dates:
 High Mountains (HM) ‚Č• 4,000 ft.
 Low Mountains (LM) < 4,000 ft.
 Piedmont (Pd)
 Coastal Plain (CP)

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Habitats and Life History
Habitats: Our one recent record comes from a floodplain terrace crossed by an extensive semi-open slough.
Larval Host Plants: Larvae feed on Broadleaf Pond-lily (Nuphar advena) (Wagner et al., 2011). Covell (1984) also lists Pickerelweed (Pontederia cordata) and cattail (Typha). - View
Wikipedia
See also Habitat Account for General Herbaceous Ponds
Status in North Carolina
Natural Heritage Program Status:
Natural Heritage Program Ranks: G4 S2S4
State Protection: Has no legal protection, although permits are required to collect it on state parks and other public lands.
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