Wild and Wonderful West Virginia Whites
It’s not a gaudy butterfly. It isn’t the biggest or the smallest. In fact, it’s mostly just white. But this butterfly is unusual; it only flies in forests. And last weekend I had the pleasure of finding 50 of these beauties nectaring, patrolling and procreating in a forest in southwestern Vermont where it is considered a species of conservation concern.
To see this butterfly you need to get to rich, mature hardwoods with spring wildflowers early in the season. Our other, more common veined white, the Mustard White, does fly in woods, but it has distinct dark veins in its first brood (when it may be confused with West Virginia White). The West Virginia White always has faint gray scaling along the veins. And, unlike the Mustard White, it only flies early in the season.
Their flight is slow and close to the ground. Follow a woodland stream until you find the host plant, — and the butterfly. It’s host plants are Crinkleroot (Cardamine diphylla), Cut-leaved Toothwort (Cardamine concatenata). Adults nectar from Toothworts, Spring Beauty (Claytonia virginica), Violets (Viola sp.), and other plants.
The West Virgina White is almost completely white above with some gray scaling on the forewing. It is whitish below with no yellow wash. The veins on the underside of the hindwing are faintly outlined in pale gray scales. It is often confused with the Mustard White, which by contrast shows distinct dark green-black veins on the underside of the hindwing during the spring flight.
West Virgina White is declining in many areas due to forestry, development, and the spread of an introduced weed called Garlic Mustard (Alliaria petiolata). Garlic mustard was first found in the United States about 1868 on Long Island, New York. Invasions of Garlic Mustard are causing local extirpations of toothwort, and chemicals in Garlic Mustard appear to be toxic to West Virgina White eggs. The adults will lay eggs on the plants but the eggs fail to hatch.
You have to hurry to see this butterfly. Like its host plant it’s a true spring ephemeral. As soon as the canopy leafs out, the adults are gone until next year.