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Pieris virginiensis, Crockford Pigeon Mountain WMA, west side of Pigeon Mountain at the Pocket, Walker Co., GA, March 27, 2020. This individual is sitting on one of the known larval foodplants for this species, Cardamine concatenata. All rights reserved, photo by James K. Adams.
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Pieris virginiensis W. H. Edwards, 1870

West Virginia White

Federal Protection: No US federal protection

State Protection: No Georgia state protection

Global Rank: G2G3

State Rank: S3

SWAP High Priority Species (SGCN): Yes

Element Occurrences (EOs) in Georgia: 7

Habitat Summary for element in Georgia: Hardwoods


Description

This butterfly, with about a two inch wingspan, is as close to an all-white butterfly as we have in the state. Males are often almost completely white (see photo, above). There can be hints of light gray shading along the veins on the underside of the hindwings, especially in females, and individuals, especially females, may also have a little hint of black scaling at the very tip of the forewings (see photo below). The live butterfly almost has a pleated appearance when resting/sitting with wings closed (see photo above).

Similar Species

There are two butterflies flying at the same time of year that could be confused with the West Virginia White, the Cabbage Butterfly (Pieris rapae) and the female Orange-Tip (Anthocharis midea), which is always a bit smaller than P. virginiensis (see photo, below). Both of these species typically have at least one black spot on the upperside of the forewing.  The underside of the hindwing in the Cabbage Butterfly is unicolorous (never with gray shading along the veins), and often more yellowish than the West Virginia White (see middle row in photo below).  The underside of the hindwing of the Orange-Tip has greenish marbling across the entire wing (see bottom row in photo below).

Habitat

The West Virginia White is a forest dwelling butterfly, as the eggs are laid on understory plants in the genus Cardamine (Brassicaceae) (see directly below). This is one of the best ways to distinguish between this butterfly and the Cabbage White. The Cabbage White is a butterfly of open fields, and so the Cabbage White may be found near, but rarely flying together, with the West Virginia White. Also, if you see a white butterfly flying in north Georgia after April, it cannot be the West Virginia White.

It should be noted, however, that the Orange-Tip is another spring butterfly and can be found flying together with the West Virginia White in forested habitats and along paths in the woods, as the Orange-Tip larvae also feed on understory plants in the family Brassicaceae.

Diet

The larvae of the West Virginia White feed mostly on plants in the genus Cardamine (Brassicaceae). Both Cardamine diphylla (Michx.) and C. concatenata (Michx.) (see photo above), plants definitively recorded as host plants for this butterfly, are found in several counties in northeastern and northwestern Georgia (USDA PLANTS database) and may be in the middle northern Georgia counties, although this requires verification. The butterfly, however, has been found at Cooper's Creek WMA in Fannin and Union Counties, and so it is likely that the Cardamine host plants are found there as well.

The adults visit various flowers for nectar, and males will also visit wet patches in the soil.

Life History

The West Virginia White is univoltine, with one generation of adults in the early Spring (mid to late March, depending on the year, through most of April, and possibly into May in the higher mountains). The adults fly in the undergrowth in the forest and along paths. Adults seem to be rather long lived, as in any given year they can be found for five to six weeks (although this may represent a staggered emergence from the pupal stage, so that different individuals are being seen in different weeks). Upon mating, the females lay egg singly (Schweitzer, et al., 2011) on various brassicaceous plants, but particularly those in the genus Cardamine, as indicated above. The larvae, which are green with a darker greenish narrow dorsal stripe and variable but typically deep green lateral stripes (Harris, 1972) develop quickly (15 to 20 days; O'Donell,et al., 2007) and pupate. The pupae diapause and overwinter, with adults emerging early the following spring, during some of the first warm days of spring.

Survey Recommendations

The West Virginia White is found in forested areas with abundant early spring understory of flowers. It seems sensitive to forest fragmentation (Schweitzer, et al., 2011), and so will likely be absent from small forest patches and areas with significant forest alteration (such as construction of wide roads, and certainly clearing or burning). As such, the butterfly should be looked for in intact second-growth forests across north Georgia. This should be done during the early spring months, when the adult is virtually unmistakable flying through the understory or along paths. In my experience, when the butterfly is found, it is usually rather numerous and easy to document.

Range

This butterfly is (or was) found from Connecticut and southern Vermont through northern New York, northern Pennsylvania and southern Ontario to northern Ohio, Michigan and northern Wisconsin. From this northern part of the range, the butterfly is (or was) found southward through the Appalachians from Pennsylvania to northern Georgia.

In Georgia, it is found only in the northern tier of counties (see map), with the most southerly records from Bartow County in northwest Georgia. The populations in Walker Co. in particular are doing very well, with large populations along both Taylor's Ridge and at Crockford-Pigeon Mountain WMA. Individuals were seen in April 2020 in the Cooper's Creek area in Fannin and Union Counties, and so these populations are currently extant as well.

Threats

As indicated above, the butterfly is sensitive to forest fragementation/alteration. It does not fly far from the forest, and therefore is unlikely to establish new colonies or re-establish older ones, if it is required to fly any distance across open habitat. 

As indicated with other species of butterflies that feed on low lying herbaceous plants, an over abundance of deer could be an issue as the deer can diminish populations of host plants available for the butterflies (Schweitzer, et al., 2011).  

As indicated for another forest dwelling species in north Georgia, the Green Comma (Polygonia faunus), the West Virginia White may be susceptible to climate change. The Georgia populations of Pieris virginiensis, which represent the most southerly populations of the species, may diminish over time as the warming climate pushes them farther north. Unlike the Green Comma however, the West Virginia White does not seem to be suffering significant populations declines at the moment.

The biggest threat to populations of Pieris virginiensis, however, is likely to be the invasive garlic mustard (Alliaria petiolata). This brassicaceous plant is toxic to the larvae, and yet the phytochemicals in the plant are strongly attractive to females of the butterfly, which readily lay eggs on the plant. Needless to say, this leads to death of all larvae that hatch from those eggs.

Spraying for Gypsy Moths (Lymantria dispar) with Btk is done in the spring, when the larvae of that moth are feeding. If the Gypsy Moth becomes established in the state, it will first be in the northern counties. As the larvae of the West Virginia White will be hatching in April, it is possible that this butterfly would be susceptible to the Gypsy Moth control measures. Care should be taken to identify Pieris virginiensis colonies before any kind of spraying is undertaken for the Gypsy Moth. Currently, this is not an issue.

Georgia Conservation Status

Some of the counties shown on the map for this species do not seem to have recent records, but I am not aware that people have actively been looking for this butterfly across much of north Georgia. As such, it is difficult to say how widespread the butterfly is currently in north Georgia, though both the Crockford-Pigeon Mountain colonies in Walker Co. and the Cooper's Creek colonies in Fannin/Union Cos. were active in spring 2020. As indicated above, the Walker Co. populations are doing very well in an area where both the Early Hairstreak (Erora laeta) and Silvery Blue (Glaucopsyche lygdamus) have been absent for several to many years. Since two of the butterflies commonly used host plants are found in several of the northeastern and northwestern counties in the state (USDA PLANTS database), the butterfly should be in most of those counties as well. This likely warrants an S3 status for the state.

Conservation Management Recommendations

The main recommendations for management of extant populations of the West Virginia White should be clear from the main threats mentioned above. The biggest threat, as mentioned above, is the establishment of the invasive Garlic Mustard (Alliaria petiolata). All attempts should be made to prevent or at least curtail the growth of Garlic Mustard wherever possible. Even in places where the Garlic Mustard has established along roadsides, but not yet invaded the forest understory, the West Virginia White has persisted, so it is particularly important to prevent invasion of the understory by this invasive plant (Schweitzer, et al., 2011).

Additionally, where there are extant colonies, significant alteration/thinning/fragementation/burning of the forest should be avoided. As mentioned above, this butterfly has a very limited capacity to establish or re-establish colonies across large open spaces. If there are populations of deer that are persistently abundant, then some culling of the herd may be helpful to this butterfly to prevent overbrowsing of foodplants. And, as mentioned above, if Gypsy Moth control is ever an issue in Georgia, then spraying should be avoided where there are extant colonies of the West Virginia White (Schweitzer, et al., 2011).

Climate change threats, however, are likely not possible to mitigate. So far, however, this butterfly seems to not be dramatically affected by such issues.

References

Harris, L., Jr. 1972. Butterflies of Georgia, pages 174-175. University of Oklahoma Press, Norman.

O'Donell, J., L. F. Gall, and D. L. Wagner. 2007. The Connecticut Butterfly Atlas. Connecticut Department of Environmental Protection, Hartford.

Schweitzer, D. F., M. C. Minno, and D. L. Wagner. 2011. Rare, declining and poorly known butterfly and moths (Lepidoptera) of forests and woodlands in the eastern United States, pages 148-153. Forest Health Technology Enterprise Team.

US Department of Agriculture website. PLANTS database. Online at https://plants.usda.gov/java/

Authors of Account

James K. Adams, Professor of Biology, Dalton State College, Dalton, Georgia

Date Compiled or Updated

Pieris virginiensis, Crockford Pigeon Mountain WMA, west side of Pigeon Mountain at the Pocket, Walker Co., GA, March 27, 2020. This individual is sitting on one of the known larval foodplants, Cardamine concatenata, with it's distinct leaves shown in this image. All rights reserved, photo by James K. Adams.
Top row: Pieris virginiensis (West Virginia White), male, female and underside. Middle row: Pieris rapae (Cabbage White), male, female and underside. Bottom row: Anthocharis midea (Orange-Tip), male, female, and underside (of a female). All specimens from either Taylor's Ridge, Walker Co., or Crockford-Pigeon Mountain WMA, Walker Co., GA, from March or April. Photo by James K. Adams, all rights reserved.