Moths of North Carolina
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View PDFNoctuidae Members: 18 NC Records

Hemipachnobia subporphyrea (Walker, 1858) - Venus Flytrap Cutworm Moth



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Taxonomy
Superfamily: Noctuoidea Family: NoctuidaeSubfamily: NoctuinaeTribe: NoctuiniP3 Number: 933545.00 MONA Number: 10993.00
Comments: Hemipachnobia is a North American genus composed of two species, both of which have been recorded in eastern North Carolina. The genus Hemipachnobia was defined by McDunnough in 1929, with H. monochromatea designated as the type species (McDunnough, 1929; Lafontaine, 1998). Although Smith (1891) tentatively listed subporphyrea as a synonym of monochromatea, other authors treated the two species as belonging to separate genera until relatively recently (Hall and Sullivan, 2000).
Species Status: Hemipachnobia subporphyrea was described (as Mythimna subporphyrea) by Walker (1858), based on an apparently now vanished male specimen in the British Museum (Lafontaine, 1998). This specimen, along with two additional females in the British Museum -- one now designated as a lectotype by Lafontaine (1998) -- were identified as having come from “Georgia” but no other collection data was given, including the identity of the collector. Forbes (1954) treated subporphyrea as a subspecies of monochromatea, although he probably never saw the type specimens of subporphyrea. Lafontaine (1998) was the first to formally recognize the two moths as separate species within Hemipachnobia, based at least partly on the discovery of genitalic differences by McCabe and Schweitzer (Hall and Sullivan, 2000).
Identification
Field Guide Descriptions: Not included in either field guideOnline Photographs: MPG, BugGuide, iNaturalist, Google, BAMONATechnical Description, Adults: Lafontaine (1998); Hall and Sullivan (2000)Technical Description, Immature Stages: Hall and Sullivan (2004); Wagner et al. (2011)                                                                                 
Adult Markings: Hemipachnobia subporphyrea is a medium-sized, purplish to reddish brown Noctuid. Head and thorax are concolorous with the ground color of the forewings, which varies from a wine-red shade (a sub-purple", as implied by the species name) to a somewhat rustier shade similar to that of H. monochromatea. Variable amounts of grayish or fuscous scales are mixed in with those of the ground color and there is also a variable but lesser amount of white scaling, both on the wings and thorax. The fuscous scales tend to be most prominent along the veins and in some specimens form conspicuous gray lines. The only obvious markings on the forewings of either species of Hemipachnobia are the antemedian and postmedian lines of the forewings; other spots and lines are completely obsolete,including the orbicular and reniform spots that are usually prominent in Noctuids. The antemedian and postmedian are composed of scales that are either only slightly darker than the ground color, or are a distinctly darker, more fuscous shade than the ground color. Both lines tend to be bordered by white scales, which precede the antemedian and follow the postmedian. In some specimens, the lines are indicated primarily by the white scales (Hall and Sullivan, 2000). Lafontaine (1998) stated that the postmedian is less serrated in monochromatea than in subporphyrea, but in several specimens examined by Hall and Sullivan (2000), the postmedian was as even, or more so, in subporphyrea than in monochromatea. Apart from size, which appears to be consistently different between the two species, other features of the wing patterns overlap at least in some specimens, and we recommend that their identities be established through dissection of the males. Within the range of H. subporphyrea, only a few other spring-flying moths are even remotely similar. Cerastis tenebrifera, which flies about a month earlier in the spring than H. subporphyrea, has bipectinate antennae in the males but is a much deeper maroon than Hemipachnobia and has conspicuous, pale orbicular and reniform spots. Trichosilia manifesta, which flies at the same time as H. subporphyrea, also has bipectinate antennae in the males and has a reddish color phase that resembles Hemipachnobia to some extent. The dark orbicular and solid reniform spots possessed by this moth, however, easily distinguish it from Hemipachnobia, as do the distinctive traits of the tribe Agrotini, to which this species belongs.
Adult Structural Features: The differences separating males of subporphyrea and monochromatea were discovered by Timothy McCabe and Dale Schweitzer (Schweitzer, 1996) and were formally described and illustrated by Lafontaine (1998). The valve in male subporphyrea has three prominent distal projections, while the valve in monochromatea has only a single distal projection. The juxta of subporphyrea has a triangular, wedge shaped posterior projection, while the juxta of monochromatea, possesses a narrowly conical posterior projection. According to Lafontaine (1998), key differences also separate the females of subporphyrea and monochromatea, with the ductus bursae heavily sclerotized and anteriorly enlarged in subporphyrea and lightly sclerotized and anteriorly tapered in monochromatea.
Structural photos
Adult ID Requirements: Identifiable from good quality photos of unworn specimens.
Immatures and Development: In a rearing study conducted by Hall and Sullivan (2004), eggs obtained from a wild-caught female were opalescent white and sculptured dorso-ventrally with approximately 35 narrow ribs (larvae were photographed in each instar. First instar larvae typically have a yellowish-brown ground color. No lines are evident in this stage but there are rows of conspicuous blackish tubercles on each segment, out of which grow long, dark setae. The tubercles on the second and third thoracic segments are arranged in a single file, but there are two rows on the first thoracic and on all the abdominal segments, with the tubercles forming an alternating series between them. Second instar larvae are quite different in appearance. The ground color is now a coral pink. The tubercles are less prominent but still present and there are now several light lines running down the length of the body. In addition to a prominent mid-dorsal line, there are two well-marked sub-dorsal lines and a lateral line just above the prolegs. By the end of this instar, the larvae have taken on the thickened appearance typical of cutworms and show some degree of differentiation between a darker dorsal surface and lighter sides. Additional light lines may also be present in between the more prominent lines developed earlier. Third instar larvae are still somewhat translucent, like the earlier instars. The head is pinkish ivory with black ocelli. The ground color of the body is initially a fairly uniform light peach color but later becomes more divided into a series of green and tan stripes. The dorsal, subdorsal and lateral stripes are still ivory in color. The dorsal and lateral stripes are still prominent, and as in the later stages of the second instar, there are now two prominent lateral lines. The subdorsal stripes still visible but are relatively less well marked than the dorsal of lateral stripes. All ivory longitudinal lines are bordered on both sides by brown lines except the lateral line which has none on the ventral side. Between the subdorsal and lateral longitudinal stripes there are 3 cream stripes and 4 darker brown, with the stripe above the lateral lines typically darker than the rest. The 8th abdominal spiracle is the largest followed by the thoracic spiracle and then the other abdominal spiracles. The prolegs are rose colored and tipped with a grey spot. There are also grey spots above them on the body. The prolegs get slightly larger posteriorly. The ventral color of the abdomen is light tan. Fourth through sixth instars are generally browner and more opaque than the earlier stages and the subdorsal ivory lines more obscure, if present at all. Otherwise the pattern remain fairly constant, with some inter-individual differences.. The mid-dorsal line and the double lateral lines remain prominent features. The yellow mid-dorsal stripe is bordered laterally with brownish-black blotching running more-or-less continuously from the head to the anus. The same blotching repeats ventrally of the subdorsal pale line to the spiracles, which are black. The blotching gives a striped appearance to the body. Ventral of the spiracles, the coloration is a light tan with occasional specks and blotching. In some cases, the tan color of the ventrum extends well up on the sides and, along with the two light lateral stripes, gives the body a two-toned appearance, with a darker dorsum and lighter flanks. In other cases, the lighter area on the sides is more confined (perhaps related to amount of feeding?). The head is tan with blotches of very small speckles in an asymmetrical pattern. The labrum is paler, clear of markings and pinkish cream in color. The ommatidia are ruby colored or black. The larvae are extremely slow growing, as was noted by David Stephan, the first to rear this species. No diapause was observed; larvae fed throughout the entire study period. This contrasts with the behavior of its congener, H. monochromatea, which enters a diapause in the second instar (T. McCabe, pers. comm.). Unfortunately, none of the larvae ever pupated.
Larvae ID Requirements: Identifiable from close inspection of specimens or by DNA analysis.
Distribution in North Carolina
Distribution: In North Carolina, H. subporypyrea appears to be confined to the Outer Coastal Plain; efforts to find it in the Fall-line Sandhills at Fort Bragg, where the westernmost populations of Venus Flytrap occur, were unsuccessful.
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: Hemipachnobia subporphyrea is univoltine: adults have been captured as early as March 24 and worn specimens have been taken as late as May 9. The majority of records are from mid-April (Hall and Sullivan, 2000).
Habitats and Life History
Habitats: All of our records come from Longleaf Pine savannas and flatwoods. All but one come from sites where populations of Venus Flytraps exist and the one exception came from an area where flytraps may have existed at the time of the capture -- a specimen of Photedes carterae was collected at the same site and it feeds solely on Pinebarrens Reedgrass, a species that is usually found in close association with flytraps.
Larval Host Plants: Aubrey Shaw (pers. comm. to SPH) found larvae feeding on cultivated flytraps growing under semi-natural conditions on his farm in Bladen County and near where he had originally collected his plants. Although he occasionally found larvae on his plants as early as the 1970's, the caterpillars were particularly numerous in 1986 and did extensive damage to his plants. Two larvae he collected were given to David Stephan for determination (D. Stephan, pers. comm.). Stephan subsequently reared both larvae to adulthood, feeding them solely on flytraps. In the rearing study conducted by Hall and Sullivan (2004), larvae were successfully fed on Sundews -- the host plant of H. monochromatea -- and later instar larvae did well feeding on Vaccinium crassifolium, a procumbent heath that grows abundantly at sites where subporphyrea has been recorded. In this regard, subporphyrea may show a switch in host plants similar to that observed in monochromatea, which Hooker (1919) observed to switch from using sundews in the earlier instars to cranberry in the later stages. Larvae of subporphyrea have not been observed in the wild (despite several search attempts), and it is not known if they feed naturally on either sundews or Vaccinium crassifolium. However, no populations of the moth have yet been found at sites where only sundews are present, at least in North Carolina.
Observation Methods: Comes at least sparingly to blacklights but efforts to collect it using bait have not worked so far. Larvae have been searched for on several occasions but have yet to be found in natural conditions in the field (specimens found by Aubry Shaw and David Stephan were collected in artificial flytrap growing beds).
Wikipedia
See also Habitat Account for Wet, Sandy, Fire-maintained Herblands
Status in North Carolina
Natural Heritage Program Status: SR
Natural Heritage Program Ranks: G1 S1?
State Protection: Listed as Significantly Rare by the Natural Heritage Program. That designation, however, does not confer any legal protection, although permits are required to collect it on state parks and other public lands.
Comments: This species appears to be extremely rare globally, not having been collected between the late 1700s and 1974, when a population was rediscovered in North Carolina. Since then, populations have been recorded at only five more sites in North Carolina and only one has been found outside of this state, by John Glaser in Maryland in 1998. Until Glaser's discovery outside the range of Venus Flytraps and the discovery by Hall and Sullivan (2004) that North Carolina larvae could also feed on sundews, the association between subporphyrea and Dionaea muscipula seemed very strong and provided a good explanation for the rarity of this species: flytraps do not naturally occur beyond a 100 mile radius of Wilmington, NC and their distribution has been greatly fragmented and reduced with the destruction of Longleaf Pine savannas. Even within surviving areas of natural habitat, the combination of fire suppression and poaching has eliminated many populations of this plant, as well as, presumably, populations of the moth -- at least one population discovered in the early 1990s appears to have been extirpated due fire suppression. On the other hand, the moth does not appear to survive through a fire; in areas that have been burned on an annual basis -- even where supporting very large populations of the flytraps -- no Hemipachnobia have been found even after intensive sampling efforts. Like many moths associated with fire-maintained savanna habitats, subporphyrea is likely to depend on a metapopulation strategy to survive disturbances to its habitats. With flytrap populations becoming increasingly small and isolated, that strategy is becoming increasingly hard to follow. If it were actually using sundews in addition to flytraps, it would have a greater chance of survival. However, we have yet to find any populations of this moth in North Carolina where only sundews exist and no flytraps. Although there is still much to be learned about this species, it currently appears to be one of our most endangered species.

 Photo Gallery for Hemipachnobia subporphyrea - Venus Flytrap Cutworm Moth

Photos: 5

Recorded by: SPH and JBS on 2001-04-19
Carteret Co.
Comment: Live male caught in a live trap.
Recorded by: SPH and JBS on 2001-04-19
Carteret Co.
Comment: First instar larvae feeding on a flytrap. Reared from eggs obtained from a wild-caught female collected on 2010-04-19.
Recorded by: SPH and JBS on 2001-04-19
Carteret Co.
Comment: Egg and early instar larvae. The bottom two shots are of a larva reared on Sundew
Recorded by: SPH and JBS on 2001-04-19
Carteret Co.
Comment: Mid to late instar larvae
Recorded by: SPH and JBS on 2001-04-19
Carteret Co.
Comment: Last instar larvae; the dark one is pre-pupal