Weidemeyer's admiral

Description

The Weidemeyer's admiral is a fairly large butterfly, between two and three quarter to three and three eighths inches wide. The upperside is black, and both wings (front and hind) are crossed by broad white bands. There is a tiny amount of blue scales on the lower edge of the hind wings. On the front and hind wing edges, there are small white spots that line a black border. A singular white spot is located on the forward edge of the front wing. The undersides are grayish white with dark veins that run through the wings. A subterminal band is colored with red cells. The terminal edge of the hind wing has black cross lines inside a white band.

Range

The Weidemeyer's admiral occurs in the Rocky Mountains and adjacent lowlands, from southeast Alberta to eastern Oregon and Nevada to the Dakotas, Nebraska and New Mexico.

Flight

There are one to two broods per year, from late May or June through August or up to November during mild autumns.

Habitat

This butterfly occurs along streams and rivers that are lined with willows or cottonwoods. It may occur in the mountainsides with nearby streams or in parklands, gardens, sand hills and sagelands.

Food

Caterpillars feed on willows (Salix) or cottonwoods (Populus), including aspens. The caterpillars may also be found on ocean spray (Holodiscus), chokecherry (Prunus) or serviceberry (Amelanchier). Adults feed upon nectar of snowberry (Symphoricarpos) or rabbitbrush (Chrysothamnus) as well as tree sap or carrion.

Life Cycle

Eggs are deposited on the undersides of leaves of the Willow family (Salicaceae), mostly willow, and cottonwood or aspen. The caterpillars are a mottled gray and white with a humped back and bristlelike spines that resemble antennae on the second thoracic segment. The caterpillar has a red- to brown-colored head. In some areas, caterpillars overwinter in their third stage of life. This is known as diapause, literally a pause in their development. The caterpillar rolls up within a leaf, then emerges in spring to molt and pupate. This leaf "sleeping bag" is known as a hibernaculum. The chrysalis resembles a bird dropping suspended from a leaf or twig, in the hopes that it will not be preyed upon. These caterpillars do not use silk to attach the chrysalis to a twig, but they have a cremaster, or hooklike structure, that secures them to a leaf or twig.

Notes

Like some other members of the Brush-footed family, Weidemeyer's Admirals can be very territorial, chasing mourning cloak butterflies, Tiger swallowtail butterflies, crescentspot butterflies or even dragonflies from their territory. The males do not patrol their territories actively like some butterflies. Instead, they perch in trees or shrubs to watch for competitors or receptive females.

This species has recently been added to the Canadians’ federal list of endangered species.

These butterflies are closely related to the viceroys (Limenitis archippus) and the Red admiral (Vanessa atalanta).

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