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Species at Risk Database

Species at Risk Database

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West Virginia White Butterfly

Pieris virginiensis

COSEWIC Status: Not at risk

COSSARO Status: Special Concern

Credit: Rick Snider

Description

  • Unlike the Monarch, this butterfly is easily overlooked. It is only 3-4 cm in size and is dingy white.
  • Wings have a translucent appearance and on the underside of the hind wing, the veins have grey-brown scaling.
  • Caterpillars are yellow-green with a green stripe along each side.

Habits and Reproduction

  • One of the first butterflies active in the spring. Flight period is quite short and only once per year. In Ontario, the recorded flight period has been April 4 to June 13th.
  • Larva feed only on the leaves of toothwort which is a small spring blooming plant.

Habitat

  • Moist deciduous woodlots.

Threats

  • Known only in roughly 50 sites in Ontario, it was likely never common in the province.
  • Habitat changes at some sites have negatively affected the population.
  • Garlic mustard is an invasive plant species that may seriously harm this species. The mustard plant is related to the toothwort. When the butterfly lays eggs on Garlic Mustard, the eggs will hatch but the young will not feed on the mustard and die.

Conservation Actions

Range Map

Photo Gallery

Garlic Mustard is considered to be one of the most invasive exotic plants in Ontario.

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