Overview

Distribution

National Distribution

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

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Global Range: (20,000-2,500,000 square km (about 8000-1,000,000 square miles)) So far as known Nantucket (Mark Mello in 2004) and historically Marthas Vineyard (F.M. Jones specimens University of Delaware) off Massachusetts, eastern Long Island, New York, the New Jersey pine barrens from about Lakehurst south to northern Atlantic County; part of the Maurice River ultraxeric sand system in Cumberland County, New Jersey; a few localities in southeastern and sandhills regions of North Carolina, and at least historically farther south in South Carolina (McClellanville) and supposedly Atlanta, Georgia (Dyar, 1921). The latter more likely came from sand hill areas to the southeast of Atlanta. The USNM also has a 19th century male supposedly from Washington, D.C. This species is not expected in Delaware, Maryland or probably Virginia now, although it probably did occur in southeastern Virginia originally. Falsely reported often for Florida, and it is possible the old "Florida" specimen cited as a syntype of the synonym H. georgiana Dyar (1921) really was from present day Florida but it could as easily have been from what is now Georgia, to be expected in the Florida panhandle.

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Physical Description

Diagnostic Description

Males must be confirmed by an expert and genitalia may need to be examined. The shiny gray color of females and larval pattern (Forbes, 1948) are distinctive but identifications should be confirmed by an expert or by comparison to a reliably identified collection. As Dyar (1921) correctly points out in describing the synonym H. georgiana "in the present species, the sexes are similar" making females easy to identify. Color difference (forewing more slate gray, hindwing brighter white with less dark markings) in males is occasionally obvious, but not usually. See Forbes (1948) for an external male genitalia character. H. obliqua larva is well illustrated by Wagner et. al (1996). H. varia larvae resemble the green form but the dorsal saddle marking is not nearly as constricted. Kimball (1965) illustrates both sexes of H. obliqua as H. varia.

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Ecology

Habitat

Comments: Habitat on Long Island New York is dwarf pine barrens where scrub oak is obviously the foodplant. Habitat on Marthas Vineyard and Nantucket off Massachusetts is similar except the pines are not dwarf. Similar habitats are used in New Jersey also, although scrub oak tends to be replaced by blackjack oak. In the New Jersey Pine Barrens region more typical pine-oak scrub habitats with either or both of these oaks dominant in the understory and post oak often common are also used widely. Any pine canopy is usually under 50%. In Cumberland County, New Jersey a disjunct population occurs on the ultraxeric Manumuskin River sands in sparse tree oak-short leaf pine woodland where post and black oaks dominate and dwarf chestnut oak is a major component of the shrub layer. This site is apparently too xeric for scrub or blackjack oak to thrive. Almost all tree oaks there are in poor condition. One other New Jersey site is an airport approach zone where the oaks are mowed in winter every one or two years (since the early 1940s) and scrub oak dominates. The habitat in the Carolinas and Georgia is less well undocumented but is/was at least sometimes sand hills oak scrub which is usually dominated by turkey oak. All habitats then are xeric to ultraxeric, sandy and characterized by scrubby, often highly stressed, oaks. Species of oak does not appear to be crucial and post, dwarf chestnut, and scrub oak are all known foodplants in nature, and are all much more widespread and common than this moth. Blackjack and black oaks are probably used as well in New Jersey.

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Migration

Non-Migrant: No. All populations of this species make significant seasonal migrations.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

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Trophic Strategy

Comments: Larvae feed on mature oak leaves. Only three records of natural foodplants identified to species in the wild are known in New Jersey: an egg on post oak (QUERCUS STELLATA) and two larvae (in different years) on dwarf chestnut oak (Q. PRINOIDES) (adults reared from both oaks for confirmation). Scrub oak has been documented on Marthas Vineyard and is obviously the main host on Long Island. Larvae have been reared in sleeves on post, scrub, dwarf chestnut and black oaks from the Cumberland County, New Jersey population and do well on all four, taking about a day or two longer to mature on black oak. Hatchlings also readily accept, possibly even prefer, blackjack oak, but that species was not available for rearing. Last instar larvae clearly prefer post and scrub oaks over willow oak, but will accept the latter. Several authors give the foodplant as "oak" probably based on Dyar (1921) who does not state the species involved.

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Population Biology

Number of Occurrences

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: 21 - 80

Comments: Virtually impossible to define occurrences in the core of the New Jersey portion of the range where this species is actually fairly common over a signifcant portion of Ocean and Burlington Counties and extreme northwestern Atlantic County. Otherwise single populations are known in New York and Massachusetts, two more farther south in New Jersey and about three in North Carolina. There are old specimens from South Carolina and Georgia but all Florida specimens examined by Schweitzer as of about 1990 are really H. obliqua as were both illustrated by Kimball (1965). There presumably are additional occurrences in the Carolina and Georgia sand hills and maybe elsewhere. There are old specimens from elsewhere on Long Island, New York and the species probably still does exist on Marthas Vineyard, Massachusetts.

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Global Abundance

100,000 to >1,000,000 individuals

Comments: Seems to be fairly numerous where found and habitats are usually large. Surely at least thousands of, and possibly >100,000, adults in the isolated New Jersey occurrence and probably more than a million in the core of the Pine Barrens most years. In New jersey this is a common moth in xeric oak scrub.

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General Ecology

Pupation is several inches deep in the soil and pupae may overwinter at least up to three times before eclosing. Thus there is always a resevoir of pupae safe from even hot crown fires. This species can be found in numbers as little as two years or much more than twenty years, probably over 50 years, after fires.

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Life History and Behavior

Cyclicity

Comments: New Jersey Pine Barrens collection dates are mostly in late May to mid June and in late July to mid August suggesting two broods but there are records in between. Collections in the Manumuskin area so far suggest a shorter flight period in June and July there. New York dates are in July. Schweitzer's larvae (from Manumuskin) entered the soil for pupation as early as 14 July, 1995 and did not eclose the same year. Adults from these 1995 pupae eclosed late June into early August of 1996, 1997 and 1998. So there may be only one brood in New Jersey. Adults do occur there every year. North Carolina specimens (USNM) include late August adult dates suggesting there is/was a second brood there and Dyar (1921) gives dates for larvae (presumably late instars) from June 2 to September 29 from the vicinity of Atlanta, Georgia again suggesting two broods. The egg stage lasts about six to nine days, possibly sometimes longer, depending on temperature. The larval period is slightly under four to just over five weeks and larvae would be present in New Jersey from about early June through mid September. The length of the larval stage varies a bit from year to year in New Jersey with all taking at least 32 days in 1995 but most taking less than 30 (minimum 26 days) in 1999. Sleeved larvae show significant but minor differences in growth rate between trees, at least of post oak. Severe summer drought and heavy Homoptera (usually aphid) infestations appear to add a few extra days to larval growth time.

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Molecular Biology and Genetics

Molecular Biology

Statistics of barcoding coverage: Heterocampa varia

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 0
Specimens with Barcodes: 9
Species With Barcodes: 1
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Conservation

Conservation Status

National NatureServe Conservation Status

United States

Rounded National Status Rank: N3 - Vulnerable

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NatureServe Conservation Status

Rounded Global Status Rank: G3 - Vulnerable

Reasons: This species is not now threatened northward. However less than ten occurrences are known extant outside of New Jersey and it is now historic in two of the six states with verified records. So this species is reasonably considered globally uncommon based on recent documentation. It global area of occupancy is probably on the order of 100,000-300,000 hectares with most of that in New Jersey. H. varia is fairly common in the New Jersey Pine Barrens and this obviously functions as a single very large metapopulation. There are also two viable occurrences slightly to the south in that state, the one in Cumberland County has probably been disjunct for millennia and has adopted a different phenology and tends to produce larger adults. Some additional occurrences will be found in the Carolinas and Georgia and if in fact the species proves to be a lot less rare there than it is now thought to be, it might be considered globally secure.
This species is not now threatened northward. However less than ten occurrences are known extant outside of New Jersey and it is now historic in two of the six states with verified records. So this species is reasonably considered globally uncommon based on recent documentation. It global area of occupancy is probably on the order of 100,000-300,000 hectares with most of that in New Jersey. H. varia is fairly common in the New Jersey Pine Barrens and this obviously functions as a single very large metapopulation. There are also two viable occurrences slightly to the south in that state, the one in Cumberland County has probably been disjunct for millennia and has adopted a different phenology and tends to produce larger adults. Some additional occurrences will be found in the Carolinas and Georgia and if in fact the species proves to be a lot less rare there than it is now thought to be, it might be considered globally secure.

Environmental Specificity: Very narrow to narrow.

Comments: While the foodplant oaks are common and wisespread this species is restricted to essentially the scrubbiest, most xeric oak dominated habitats in its range.

Other Considerations: High probabilty for some addtional extant populations to turn up in the Carolinas. South of New Jersey high quality habitats for this and most other rare oak feeders tend to be despised by many land managers and excessivley burned for conversion to more herbaceous savannas or managed for commecial pine farms. This and assocaited rare Lepidoptera thus may be quite imperiled by land management on many or most "protected" sites.

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Global Short Term Trend: Relatively stable to decline of 30%

Comments: Seems basically stable in New Jersey, and north of there although this could possibly change with fire suppression and substitution of light winter burns for hot wildfires since many currently good habitats are pyrogenic scrublands and the species is not common in more mature oak-pine forests with minimal understory maintained by most light winter burns.

Global Long Term Trend: Decline of 50-90%

Comments: Outside of New Jersey and the Massachusetts islands this species has lost an overwhelming majority of its roginal habitat. In those two states perhaps 25% has beeen lost.

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Threats

Degree of Threat: Medium

Comments: Not very threatened in at least the next few decades in Massachusetts, New York or New Jersey. Southward xeric oak scrub continues to be herbicided, plowed, and chopped, to make way for pine plantations, but most such areas already have been destroyed. Known Carolina occurrences are in Parks or preserves. In some cases preserve managers burn scrub habitats excessively trying to convert them to savannas. It is likely though this practice reduces rather than eliminates H. varia. Gypsy moth spraying with persistent chemicals, but not BTK, would impact this species, as might gypsy moth defoliation. In New Jersey most habitats for this moth do not support gypsy moth outbreaks. Wildfires or prescribed burning would cause little or no direct mortality from about October through April or May since pupae are several inches deep in the sand and whether fire is a threat or a benefit depends on what kind of community results. In the long term lack of wildfire could threaten this species in parts of New Jersey. Since a majority of pupae overwinter at least twice before eclosing (Schweitzer, unpublished) there is always a reservoir of this stage making populations resistant to any single disturbance.

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Management

Global Protection: Few to several (1-12) occurrences appropriately protected and managed

Comments: TNC protects most of New York habitat and over 550 ha in the Maurice River system site. Additional lands in NJ seem reasonably protected for now but none have adequate long term fire plans. Some degree of protection at both Massachusetts sites.

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Relevance to Humans and Ecosystems

Risks

Stewardship Overview: Maintain scrub habitat with occasional to frequent fires, but also consider other species. The main need seems to be maintaining xeric oak scrub with sparse pine cover or as treeless scrub. Direct mortality to fire should be zero to pupae which are present year round deep underground (some overwinter three times before eclosion--Schweitzer). The entire population is pupae from about mid September to mid May in New Jersey. Fire mortality to other stages would be virtually 100% in scrub habitats. These occur about late May to early September in New Jersey, although individual adults live only a few days and the egg and larval stage together is about five weeks. A more important consideration than direct mortality from fires is habitat changes caused by fires. In some habitats these will clearly benefit this and other oak scrub specialists by maintaining an open aspect, but excessively frequent fires that reduce oaks to relatively weak sprouts probably are detrimental especially when the canopy remains intact. It is possible, but is not at all documented, that areas where top-killed oaks are recovering from fires by vigorous sprouting may be particularly good habitats. It is certain such places are occupied. It is also certain that some habitats do not need frequent burning and probable that some others do. With large tracts, age class heterogeneity is recommended.

In and north of New Jersey all known occurrences occupy more than 1000 hectares of high quality oak scrub or woodland. Populations there thrive in areas burned several times per decade, or not at all in over 50 years. Fires are infrequent but can top-kill all oaks farther north. This moth pupates deep in the sand, and so fires are unlikely to cause direct mortality. With the exception of complete fire suppression or annual summer burning, it is unlikely any fire regimen would eradicate populations as long as the oaks continue to resprout. Areas cutover or burned in winter or spring are excellent habitat by the first summer, at least in the case of scrub and blackjack oaks. Optimal habitats in most of the range rarely to never support gypsy moth outbreaks, probably because the oaks leaf out too late in the spring. BTK applications in spring would probably cause little or no mortality to H. varia. Obviously silvicultural practices that kill the oaks would severely impact populations. Timber harvest should not greatly impact populations as long as scrubby oaks are undamaged or allowed to re-sprout.

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Names and Taxonomy

Taxonomy

Comments: This species is seldom correctly identified. The fact that Kimball (1965) illustrated both sexes of H.obliqua as H. varia greatly added to the confusion. Genitalia of both sexes differ as do the larvae (Forbes, 1948). Larval differences have been verified by Schweitzer who reared both species in 1995 and subsequently in New Jersey. Identification of males must be confirmed by an expert as these are genuinely difficult and may require dissection. Females are very distinctive. While misidentification has been a problem, the actual taxonomy is not confused or in doubt. D.Schweitzer

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