occurs (regularly, as a native taxon) in multiple nations
Regularity: Regularly occurring
Type of Residency: Year-round
Regularity: Regularly occurring
Type of Residency: Year-round
Global Range: (200,000-2,500,000 square km (about 80,000-1,000,000 square miles)) The species ranges from southern and western Vermont to south central Connecticut west through northern Pennsylvania and New York (but with a gap between northern and southern populations) to northern Ohio, across southern Ontario to Michigan and northern Wisconsin, and down the Appalachians from Pennsylvania to northern Georgia. Populations also occur a limited area near the Ohio River in Indiana and Kentucky (Opler, 1992). The West Virginia white is probably extirpated in southwestern Connecticut and southeastern New York (Cech and Tudor, 2005), New Jersey (Gochfeld and Burger, 1997), and eastern Pennsylvania (David Wright). LeGrand and Howard (2010) report an "alarming decline", in the northern and central Appalachians possibly as far south as northern North Carolina but the species may still persist there. Thus the range is likely to become fragmented and may already have shrunk considerably. Populations in Connecticut through Pennsylvania and down the mountains are probably especially in jeopardy.
The dark wing veins beneath will immediately separate this butterfly from the introduced Cabbage White which also usually has prominent black spots on the forewings above. Separation from the Veined (or mustard) white (Pieris oleracea) is much more difficult northward where their ranges overlap. Veined Whites have the wing veins beneath much darker and often the color of the hindwing beneath more yellowish white. They are not really separable from above but generally Veined Whites will have the dark areas much blacker.
Comments: Typical habitats are mesic hardwood or hardwood-northern conifer-mixed forests on rich soils. Also can occur in hardwood swamps. Obviously an important feature is plentiful suppply of the foodplants, generally toothworts, over a substantial area. Colonies do not occur in any kind of open habitat and adults do not readily leave the forests or cross powerlines, unshaded roads etc. They will cross forest roads and jeep trails which have a canopy abovve them and may even fly along such roads. The species is more likely to occur if there are many substatial foodplant patches in a large tract of unbroken forests which can sustain a metapopulation.
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.
Unusually sedentary in most contexts. Adults will not enter open areas although they will move rather freely within forests and do stray away from the foodplants.
Comments: The larvae feed on small forest plants in the mustard family (Brassicaceae). By far the most commonly reported foodplants are toothworts, which are now placed in Cardamine but are better known as Dentaria. Two-leaved toothwort (Cardamine diphylla) is the most commonly reported foodplant, but cut-leaved toothwort C. concatenata (=Dentaria laciniata) is often reported, narrow-leaved toothwort (C. multifida) is also used in Ohio, and rock cress (Arabis laevigata) is the primary foodplant for a few populations there (Iftner et al. 1992). Allen (1997) reported oviposition on other species of these genera in West Virginia, but some of these may not be successfully used by larvae, and he also reported garlic mustard, which is now known to be toxic. Adults feed on nectar from a variety of herbaceous spring will flowers including garlic mustard and the larval foodplants. They also drink from moist soil.
Number of Occurrences
Note: For many non-migratory species, occurrences are roughly equivalent to populations.
Estimated Number of Occurrences: 81 to >300
Comments: Number of occurrences is rapidly declining in some parts of the range, but so far not at the northern edge or westward. This is a summary of the known current status as of about 2010. Robert Dirig reports four known extant populations in Tompkins County and one each in Broome and Delaware Counties as of 2010, with others that probably are still extant in Broome, Cattaraugus, and Lewis Counties at least as recently as 2005. One of these sites is a wildflower garden on the Cornell Campus which was colonized around 1990. As far as known, West Virginia white is still stable in Ontario and the northern Midwest--it is still present. As of 2002-2010 the West Virginia white is still being found in its historic range in Vermont (Vermont Center for Ecostudies, accessed August, 2010, Michael Sabourin, pers. comm., August 2010, Kent Macfarland, pers. com., September 2010). Photographs of West Virginia whites taken in 2007 in four different towns appear on the Massachusetts Butterfly Club Website as of September 2010. So there are still dozens of colonies in this portion of the range and probably also in Ontario. The Connecticut Butterfly Atlas (O'Donnell et al., 2007) did not detect much difference between its historic and 1995-1999 range there, but noted some colonies extant then may no longer exist. John Shuey (pers. com.., 2010) reports that West Virginia white still occurs fairly widely in suitable habitats in southern Indiana. Similarly the species is still found in the mountains of southwestern (but not northern) North Carolina and eastern Tennessee (LeGrand and Howard 2010), including Great Smoky Mountains National Park. However, in its core range, widespread decline or extirpation is reported. The West Virginia white is probably extirpated in southwestern Connecticut and southeastern New York (Cech and Tudor, 2005), New Jersey (Gochfeld and Burger, 1997), and eastern Pennsylvania (David Wright). LeGrand and Howard (2010) report an "alarming decline", in the northern and central Appalachians possibly as far south as northern North Carolina.
Life History and Behavior
Comments: This butterfly has one generation per year, with peak adult numbers present for less than a month before and while the canopy closes. The flight season is mainly in April or May depending on local climate and weather. Eggs are laid singly on the underside of foliage of the foodplant, and larvae eat the leaves. The duration of the egg stage is 3 to 8 days (O'Donnell et al., 2007)) and larval stage is 15 to 20 days, depending on weather. The foodplants senesce in late May or June so larvae from late eggs are in a close race to complete feeding in time, and in dry springs some of them do not. The summer, fall, and winter are spent as pupae, and it is suspected, but not documented, that some overwinter more than once. Very rarely a few adults eclose in early summer but it is unlikely they can successfully reproduce then due to lack of foodplant.
Molecular Biology and Genetics
Statistics of barcoding coverage: Pieris virginiensis
Public Records: 0
Specimens with Barcodes: 6
Species With Barcodes: 1
National NatureServe Conservation Status
Rounded National Status Rank: N3 - Vulnerable
Rounded National Status Rank: N3 - Vulnerable
NatureServe Conservation Status
Rounded Global Status Rank: G3 - Vulnerable
Reasons: This butterfly is still found regularly at the northeastern edge of the range in Massachusetts and Vermont, from central New York to Ontario in the northwest, and in parts of the Ohio Valley, at least in Indiana. It also remains fairly common in a limited area at the southwestern corner in North Carolina and adjacent Tennessee, but decline there is probably imminent (LeGrand and Howard, 2010). The West Virginia white has declined greatly or disappeared in its core range from the New York City suburbs to the northern North Carolina mountains. If the current assessment of Cech and Tudor (2005), LeGrand and Howard (2010), Robert Dirig (pers. com., 2010), and others that the increasingly invasive garlic mustard is driving the decline of this species is correct, unless the West Virginia white can adapt to that plant, it is likely to become rapidly rarer and disappear in parts of of its remaining range. For now there are probably well over 100 populations that would be viable if garlic mustard were to be controlled (which in most places is unlikely) or if the West Virginia white could adapt to it.There is weak circumstantial evidence of adaptation to garlic mustard in some places, but it is also possible garlic mustard has not invaded these forest interiors sufficiently to eradicate the butterfly. No direct evidence of larvae developing successfully on this plant was found, so the toxic decoy effect has not been refuted. Unless this butterfly can adapt to garlic mustard, the West Virginia white is at high risk of increasingly widespread extirpation and possibly extinction. Even if genetic adaptation does occur this is very unlikely to salvage smaller populations (e.g. Porter, 1994). Many populations are too isolated for any natural gene flow, and their habitats probably would mostly not be recolonized naturally. No rank really captures the current uncertainty. Reasonable choices include GU based on uncertainty as to the universality of the garlic mustard threat and/or potential for adaptation, or G2G3 (also the Rank Calculator 3.1 rank) since the species is not yet demonstrably declining in many peripheral parts of its range but is expected to do so. "G3?", which is a snapshot in time as of 2010 but acknowledges the substantial decline and uncertainty regarding the universality of the garlic mustard threat, is chosen for now. A careful evaluation of possible adaptation to garlic mustard, or lack of same, is needed where both that weed and the West Virginia white both appear to be numerous. This rank should be a high priority for frequent re-evaluation and seems likely to go to G2 within a decade.
Intrinsic Vulnerability: Moderately vulnerable
Comments: Usually somewhat patchily distributed in apparently small colonies, and adults do not often enter open areas, so the species is vulnerable to forest fragmentation.
Environmental Specificity: Narrow. Specialist or community with key requirements common.
Other Considerations: The West Virginia white also has had a history of being overlooked, especially formerly in New York and Ontario (Stanton, 2001, Layberry et al., 1998). However, there are a lot more people looking now and this butterfly's habits and habitat are much better known so this is no longer a major issue.
Global Short Term Trend: Decline of 30-50%
Comments: The West Virginia white is probably extirpated in southwestern Connecticut and southeastern New York (Cech and Tudor, 2005), New Jersey (Gochfeld and Burger, 1997), and eastern Pennsylvania (David Wright), and except in New Jersey this would be mostly since 2000. LeGrand and Howard (2010) report an alarming decline, in the northern and central Appalachians possibly as far south as northern North Carolina. However, the species is not known to be currently declining in Canada, Massachusetts, Vermont, some parts of New York, southern Indiana, or in extreme southwestern North Carolina and adjacent Tennessee, that is around most of the western and northern periphery of the range. Most of the states involved still have S3 ranks from the 1980s and 1990s.
Global Long Term Trend: Decline of 30-70%
Comments: Widely reported to be declining since at least Shapiro (1974), but Stanton (2001) makes a good case that it has been to some extent overlooked in New York as had previously been the case in Canada as well. However, his "recent" New York records extend from 1974 to 1999 and may no longer reflect status there nor do those of O'Donnell et al. (2007) for Connecticut. Based on his range map for New York and other sources (Gochfeld and Burger, 1997, O'Donnell et al, 2007, Cech and Tudor, 2001) it seems clear the species has declined or locally disappeared in Connecticut, southeastern New York, and probably at least eastern Pennsylvania (David Wright). It disappeared from New Jersey more than 50 years ago. At least as of 1999, Stanton's evidence suggests the species was not in obvious decline in other parts of New York and it was also fairly stable in its Canadian range around that time (Layberry et al., 2001) and this is apparently still the case. In central New york, Robert Dirig (pers. com. to D. Schweitzer, Sept. 2010) reports four known extant populations in Tompkins County and one each in Broome and Delaware Counties as of 2010, with others in Broome, Cattaraugus, and Lewis Counties at least as recently as 2005. The West Virginia white is still apparently stable in western and northern parts of the range, that is in peripheral areas, but not the core.
Degree of Threat: High
Comments: The West Virginia white is sensitive to forest fragmentation and because adults seldom fly into open areas, the species seldom recolonizes, although Stanton (2001) and Robert Dirig each report one case where it did in New York. Roads wide enough to create gaps in canopy cover probably effectively fragment the habitat. Nevertheless, the species was fairly widespread and not rare in second growth forests into the 1980s or 1990s. Out of control deer are probably a threat, and in many northeastern US forests virtually no native spring ephemerals still occur, although the alien garlic mustard may remain, or become, numerous. Gypsy moth spraying is potentially more of a threat to West Virginia white than to most Lepidoptera due to typical low densities and more apparently poor colonizing ability, and may have contributed to the early disappearance of this butterfly in New Jersey. The larvae are probably sensitive to Btk but this is not certain. Although it occurs in warmer climates than most North American Pieris, except in a limited area of the Ohio Valley the West Virginia white butterfly has a more northern and montane distribution than its foodplants, for example it was never found on the PIedmont or coastal plain, and is mostly a mountain species south of northern Pennsylvania. One important foodplant, Cardamine concatenata (=Dentaria laciniata), ranges to the Florida panhandle and into Texas and occurs widely on the Piedmont and into the coastal plain, being nearly statewide in Virginia. This butterfly will probably be reduced or eliminated from some of its current range by climate change (unless eliminated sooner by other factors) in the warmer parts of its range, although it might be able to move into higher elevations in a few places. There might be some potential for northward expansion in Canada if forest cover is continuous enough. Not only is warming a factor, but increasingly variable precipitation is a potential threat if short term droughts become more common. In dry springs when the foodplants senesce early, most or all larvae may starve (Cappucino and Kreiva, 1985). The larvae are also subject to viral diseases, but we cannot assess their likely impact.
The most serious threat is from the highly invasive alien garlic mustard (Alliaria petiolata) which, aside from one inconclusive, uncompleted, rearing attempt (Porter, 1994) has been found to be lethal to the larvae. Females readily oviposit on it (Chew, 1982, Courant et al., 1994, Porter, 1994, Cech and Tudor, 2005, LeGrand and Howard, 2010). The decline of the butterfly appears to have begun in the New York City area where garlic mustard was first introduced, and the disappearance of the West Virginia white coincided closely with increasing invasion of forest understories by garlic mustard since about 1990 in Fairfield County, Connecticut, adjacent southeastern New York (Cech and Tudor, 2005, Victor DeMasi pers. com. to D. Schweitzer), Slingerlands, Albany County, New York (R. Dirig) and in the "northern and central Appalachians" (LeGrand and Howard, 2010). Garlic mustard is a plausible factor in the recent decline of this butterfly in eastern Pennsylvania, but not in New Jersey where the West Virginia white probably disappeared by the 1950s.
The West Virginia white has persisted with garlic mustard for more than 15 years in New York, Vermont, Massachusetts, and Indiana at least, but at least in most such places garlic mustard is still abundant mostly along roads and not in forest interiors. Virtually all reports indicate that where garlic mustard is absent or present along roadsides and edges, but not yet abundant in forest interiors, the West Virginia white is still found reliably. Robert Dirig reports that garlic mustard is now removed annually at a Cornell University habitat. While information is not complete or current for some parts of the range, unless the West Virginia white can adapt to garlic mustard, the outlook for this butterfly appears bleak in much of the range- but perhaps not all of it. While the toxic decoy effect of garlic mustard was known by then, Stanton (2001) reasonably suggested that it is premature to dismiss the possibility of this butterfly adapting to garlic mustard, as the related Pieris oleracea apparently is doing in New England (Courant et al., 1994). So far there is no direct evidence of this happening with the West Virginia white and Porter (1994) reared larvae only to second instar on it. Nor is there any known reason to believe that currently productive habitats will remain uninvaded by garlic mustard without diligent control efforts such as at the Cornell site--although perhaps some northern and western portions of the butterfly's range will not be as severely invaded by this weed as more core portions have been. Garlic mustard removal programs are in place in some parks and preserves, but mostly not within the range of the West Virginia white.
Management Research Needs: It would be useful to know whether this species sometimes maintains pupal diapause through more than one winter as orangetip pupae commonly do. Observations that West Virginia Whites are very scarce some years and then recover suggest this possibility and many aspects of their phenology and ecology suggest this trait would be advantageous. In terms of practical considerations, if a substantial number of pupae do hold over an extra year or two, one time events like gypsy moth spraying or a single incident of extreme herbivory would be much less likely to wipe out a population. This could be investigated by rearing larvae under ambient condidtions and excellent food supply, then maintaining pupae under as close to ambient conditions as possible. Dale Schweitzer
Biological Research Needs: It needs to be determined whether the West Virginia white is adapting to garlic mustard in places, e.g. southern Indiana and parts of New England, where it has persisted since the early 1990s or longer with that weed. Adaptation could involve either host range expansion to include garlic mustard as a foodplant, or selection leading to avoidance of this plant by ovipositing females. If there has been little or no adaptation then it would be critical to determine what thresholds of garlic mustard and foodplant abundance or fine-scale distribution are compatible with persistence of West Virginia white.
Global Protection: Few to many (1-40) occurrences appropriately protected and managed
Comments: This species should not be considered protected in preserves and parks where garlic mustard is widely invasive into forest interiors (not merely along roads) and/or deer are abundant and uncontrolled. For now the Cornell University campus population and any other with annual garlic mustard removal programs can probably be considered protected.
Needs: Garlic mustard control and in some places deer control are critical needs now.
Relevance to Humans and Ecosystems
Stewardship Overview: This is a butterfly of intact rich deciduous forest floors, precisely the habitat now being rapidly lost to out of control deer and invasive plants in much of its range. The impacts of exotics to this butterfly are more direct than usual. Besides whatever impacts invasive plants have on the larvae, females of the West Virginia White will oviposit on garlic mustard, which is lethal to the hatchlings. In addition the increased abundance of garlic mustard has made the imported Cabbage White butterfly (P. rapae), for which this weed was a natural host in its native range, a fairly common adventive into forests before the canopy closes in spring. To the extent this butterfly breeds on the garlic mustard in the forests it will probably bring with it the exotic Cotesia introduced as a biocontrol. This parasitoid does kill native whites as well. The impacts of deer to this butterfly include loss of larval foodpant, direct consumption of eggs and larvae, and reduction or elimination of nectar flowers.
Management needs are primarily controlling deer and invasive plants, especially garlic mustard. West Virginia Whites will not enter open habitats so even roads and powerlines can severely fragment its habitats if they are wide enough that the canopy does not extend over them. Gypsy moth spraying is also a serious issue since all larvae would be exposed during a typical application. While there are apparently no data on the sensitivity of West Virginia White larvae to BTK, it is probably lethal to at least early and mid instars.
The West Virginia white butterfly (Pieris virginiensis) is a relatively common butterfly found in the Great Lakes states, along the Appalachians from New England to Alabama, and in southern Ontario. They are typically found in moist deciduous forests.
It has translucent whitish wings of length 4.5-5.5 cm; the hindwing underside has brownish or pale gray scaling along the veins.
- US Geological Survey: Northern Prairie Wildlife Research Center: West Virginia White Butterfly
- Bug Guide: Species Pieris virginiensis - West Virginia White
|This Pieridae-related article is a stub. You can help Wikipedia by expanding it.|
To request an improvement, please leave a comment on the page. Thank you!