Great Southern White (Ascia monuste) (Linnaeus, 1764)

Diagnosis: Large for a pierid (wingspan: 47 to 56 mm), this butterfly is clear white on the upper side except for a thin black scalloped border on the outer part of the forewing. The underside is an unmarked creamy colour.

Range: A mainly tropical species, the Great Southern White reaches into the U.S. along the Gulf of Mexico and southern Atlantic coasts. It occasionally migrates farther north into the central U.S. There is only one reported sighting for Canada, a single individual observed at close range by Alan Wormington on 16 June 1981 at Point Pelee in southwestern Ontario. That year was a notable one for southern migrants reaching Canada.

Subspecies: Subspecies monuste occurs from South America northward to Texas and is the subspecies that wanders northward, including the Ontario record. Another subspecies occurs in Florida.

Similar Species: The Tropical White (Appias drusilla (Cramer)), while not recorded from Canada, has migrated north to New York State and could occur in southern Ontario in years of heavy migration. Males are entirely white above; females have a thin even black border on the forewing.

Early Stages: The larva is green, with five orange bands along the body and an orange head. Although it feeds on a wide variety of cultivated mustards in the southern U.S., it is not likely to befound in Canada.

Abundance: There has only been one sighting in Canada; not to be expected.

Flight Season: The Great Southern White flies year round in the southern U.S.

Habits: During migration, this butterfly is usually seen in open spaces. At Point Pelee it was found, appropriately, close to the Visitor Centre (Wormington, 1982).

© 2002. This material is reproduced with permission from The Butterflies of Canada by Ross A. Layberry, Peter W. Hall, and J. Donald Lafontaine. University of Toronto Press; 1998. Specimen photos courtesy of John T. Fowler.