The major foodplants for the caterpillars of West Virginia White butterflies are two species of toothwort (Dentaria diphylla and less often Dentaria laciniata), both are common northeastern early spring woodland wildlflowers. These may be the only foodplants in New york but in some other areas rock cress (Arabis laevigata) is also used. Females will lay eggs on then invasive garlic mustard but this plant is toxic to the larvae.
Although it has been documented from 30 or more locations since the late 1990's, and additional locations are undoubtedly undocumented, this species is experiencing declines in substantial portions of its range. It appears to generally occur in small populations, depends on just two larval host plants, and is noted as not being a strong colonizer of new sites; all intrinsic factors that lead to vulnerability. The spread of garlic mustard, which is toxic to caterpillars, and the loss of foodplant populations in some areas due to overbrowsing by deer, are threats that will likely be very difficult to reduce.
Based on reported long term declines and extirpations in other parts of the species range, as well as the loss of some sites in New York since the 1950's (Shapiro 1974), it is reasonable to assume that declines are occurring, but there is little data on population sizes of individual colonies over time to support this assumption.
This species is declining, or has already declined or become extirpated, in some portions of its range. Shapiro (1974) noted that some populations in New York have apparently been extirpated since 1950, but the extent of an overall decline within the state is uncertain.
The West Virginia white is reported to be sensitive to forest fragmentation due to its poor colonizing ability and is threatened by the spread of the exotic plant, garlic mustard (Alliolaria petiolata) which may choke out stands of the the caterpillars' foodplant (toothwort, Dentaria sp.). In addition, while female butterflies will oviposit on garlic mustard, this plant is toxic to the caterpillars. Overbrowsing of toothwort as a result of very high deer densities is also a possible threat. Spraying for gypsy moth control has been and, at least in places, may continue to be a serious threat to this butterfly due to its occurrence in low population densities and its poor ability to colonize new locations (Cappuccino 1985). Logging practices which lead to the loss of stands of toothwort and destruction of toothwort stands from ATV use are possible threats in at least one region of New York (Taft 2006).
Employing forest management practices and ATV restrictions that do not contribute to the loss of toothwort stands would be desirable. Removal of garlic mustard where it occurs at or near West Virginia White colonies would be advantageous, but may only be practical on a small site by site scale.
Research on deer densities in comparison to the distribution and abundance of toothwort may provide information useful for the conservation of West Virginia White colonies. Further research on dispersal tendencies may provide information useful in minimizing fragmentation of populations due to forest and other management practices.
The West Virginia white is a forest understory species typically found in moist, rich, deciduous or mixed woods with the larval hostplant, toothwort. Many locations occupied in New York are near or along streams and the rich nature of the woods is highlighted by the presence of a host of spring ephemeral wildlflowers in addition to toothwort (New York Natural Heritage Program 2006).
This species is fairly widespread across the southern portion of the state with recent records from counties in the Catskills, Hudson Valley, and southern tier. There are also recent records from disjunct locations in Lewis County as well as poorly substantiated older records from St. Lawrence County. Since this species does occur in Vermont and northern Berkshire County, Massachusetts, it could turn up in adjacent parts of New York.
The range of the West Virginia White extends from north central Wisconsin and northern Michigan, eastward across southern Ontario and New York, to southern Vermont and New Hampshire, and western Massachusetts and Connecticut. The range also extends southwestward through the Appalachians to northern Georgia and Alabama (Opler and Krizek 1984).
The West Virginia white is a small, white butterfly with generally unmarked wings above. The wings are translucent or semi-translucent, the forewing is rounded, the veins on the hindwings are indistinctly lined with brown or gray, and there is a lack of any yellow tinting on the undersides of the wings. Overall size varies from 1.8-2.1 in. (46-54 mm). This species has a low, weak flight. Caterpillars are yellow-green with a green stripe along each side (Opler and Krizek 1984, Opler and Malikul 1992).
The color and pattern on the upperside and underside of the wings is often the best means of identification for butterflies and serves to distinguish the West Virginia white from the species it may be most easily confused with. Inew New york these generally would not occur together, but Pieris napi is less translucent, brighter and has the wing veins much more strongly darkened.
Adult butterflies are usually more easily identified than their larvae or their pupae; although the identification of caterpillars is now more possible thanks to the completion of several new field guides and other publications including Wagner (2005), Wagner et al. (2001), and Wagner et al. (1997). A pierid larva on Dentaria would probably be this species but see Allen et al. (2005) to rule out the Cabbage White (Pieris rapae).
West Virginia white butterflies fly largely within their woodland habitat and are hesitant to cross open fields (Cappuccino and Kareiva 1985) or any unshaded habitat. Within the woods, they fly with a weak flight, low to the ground, on warm, calm, sunny days in early spring. Newly emerged males will seek moist areas near streams or the damp margins of woodland roads (Cappuccino and Kareiva 1985, Opler and Krizek 1984).
Throughout its range the West Virginia white has just one brood (univoltine) which flies in the early spring and the flight season is fairly short in duration. In the northern portion of the range, adult flight dates typically range from late April to mid June (Opler and Krizek 1984). The majority of records for New York reported in recent years are from late April to mid May with a smaller number of records from early April, late May, and rarely, early June (Fiore and Wallstrom 2003, 2004, 2005, New York Natural Heritage Program 2006). The caterpillars complete feeding by early summer and the chrysalis undergoes diapause until the following spring (Opler and Krizek 1984). It is possible, but undocumented, that some chrysilids overwinter more than once before emerging.
The time of year you would expect to find West Virginia White reproducing, larvae present and active, and pupae or prepupae present in New York.
West Virginia White
Pieris virginiensis W. H. Edwards, 1870
Cappuccino, N. and P. Kareiva. 1985. Coping with a capricious environment: A population study of a rare pierid butterfly. Ecology 66(1):152-161.
Fiore, T. and K, Wallstrom. 2003. New York State Butterfly Records for 2002. New York Chapter of the North American Butterfly Association. 52 pp.
Glassberg, J. 1999. A field guide to the butterflies of eastern North America.Oxford Univeristy Press, New York, New York. 242 pp.
Layberry, R.A., P.W. Hall, and J.D. LaFontaine. 1998. The Butterflies of Canada. University of Toronto Press: Toronto, Canada. 280 pp. + color plates.
New York Natural Heritage Program. 2006. Biotics Database. Albany, NY.
New York Natural Heritage Program. 2019. New York Natural Heritage Program Databases. Albany, NY.
Opler, P.A. and V. Malikul. 1992. A field guide to eastern butterflies. Houghton Mifflin, Boston, MA. 396 pp.
Opler, Paul A. and G. Krizek. 1984. Butterflies East of the Great Plains. The Johns Hopkins University Press, Baltimore.
Shapiro, A.M. 1974. Butterflies and skippers of New York State. Search 4:1-60.
Taft, Ted. 2006. Notes regarding Pieris virginiensis surveys at Boutwell Hill, Stockton and Harris Hill State Forests 2001-2005.
Wagner, D.L. 2005. Caterpillars of eastern North America. Princeton University Press. Princeton, New Jersey. 512 pp.
Wagner, D.L., D.C. Ferguson, T.L. McCabe, and R.C. Reardon. 2001. Geometrid caterpillars of northeastern and Appalachian forests. USDA, Forest Service, Forest Health Technology Enterprise Team, FHTET-2001-10, Washington, DC. 239 pp.
Wagner, D.L., V. Giles, R.C. Reardon, and M.L. McManus. 1997. Caterpillars of eastern forests. USDA, Forest Service, Forest Health Technology Enterprise Team, FHTET-96-34, Washington, DC. 113 pp.
Information for this guide was last updated on: March 30, 2006
Please cite this page as:
New York Natural Heritage Program. 2019. Online Conservation Guide for Pieris virginiensis. Available from: https://guides.nynhp.org/west-virginia-white/. Accessed April 18, 2019.