North American Range
First proposed by a 5th grade class at the Cornwall Elementary School, the Vermont General Assembly declared the Monarch as the official state butterfly on July 1, 1987.
Adults make massive fall migrations, flying thousands of miles south to winter in central Mexico. A few overwinter along the Gulf coast or south Atlantic coast. Along the way, Monarchs stop to feed on flower nectar and to roost together at night. Some of these roosts have been observed in the Champlain Valley. At the Mexico wintering sites, butterflies roost in trees and form huge aggregations that may have millions of individuals. Most have mated before they leave for the north in the spring, and females lay eggs along the way.
Upperside of male is bright orange with wide black borders and black veins; hindwing has a patch of scent scales. Upperside of female is orange-brown with wide black borders and blurred black veins. Both sexes have white spots on borders and apex. The Viceroy butterfly (Limenitis archippus) is a Mullerian mimic; it has similar coloration and is also distasteful.
Arriving as early as mid May in some years, Monarchs probably have two generations during the summer before migrating southward in September and October. Extreme dates: 17 May 2003 in Weybridge (D. Peterson) and 1 November 2006 in Chester (M. Reiter).
Distribution and Habitat
Monarchs are found throughout the state of Vermont. They prefer open meadows, weedy areas, marshes, roadsides and disturbed habitats with milkweed. Caterpillars feed on Common Milkweed (Asclepias syriaca), Swamp Milkweed (Asclepias incarnata), and Showy Milkweed (Asclepias speciosa). Blooming later summer/early fall clover fields have been found to be important stopover habitat in the Champlain and Connecticut valleys during VBS.