By: Andrew D. Warren
On sunny, warm days, when the snow melts and vegetation starts to grow, butterflies are plentiful in the San Juan Mountains. Find them in canyons, on shrubby hillsides and in flower-filled meadows below and above timberline. Most often seen on flowers and on damp ground at the edges of creeks and ponds, 116 different species of butterflies occur in the San Juans above 9,000 feet. Of these, all but 13 stray species (which are seasonal visitors) spend their entire lives in the San Juans. For most of these, winter is spent as a larva or a pupa, generally under stones or other ground cover. The few species that hibernate through the winter as adults are the first species to be seen in the spring (Mourning Cloak and Milbert’s Tortoiseshell).

Many of our butterflies thrive in specialized habitats above timberline. The cycle, from egg to larva to pupa to adult, generally occurs yearly, although a few species have two generations each season. Some fly only early in the spring, but most species in the San Juans are active as adults in July and August. A few species require two years to complete development and only fly every other year (the Grizzled Skipper only flies in odd- numbered years in Colorado). As larvae (caterpillars), butterflies feed on the leaves and flowers of local trees, shrubs and grasses.

To identify butterflies, obtain a copy of "Butterflies of the Rocky Mountain States" by C.D. Ferris & F. M. Brown. 1981. Oklahoma: Oklahoma Univ. Press or National Audubon Society Field Guide to North American Butterflies by R. M. Pyle. 1981 & 1995. New York: Chanticleer Press, Inc.

The following resident species spend their entire life cycles in the San Juans: from egg, caterpillar, chrysalis (pupae), to final flight as a butterfly.

In the family Hesperiidae-Skippers (9,000 to 13,500 feet:): Mexican Cloudywing; Dreamy, Telemachus, Pacuvius and Persius Duskywing; Xanthus, Checkered, Garita, Colorado, Nevada, Draco, Sonora, Woodland, Taxiles, Snow’s and Dun Skipper. In the family Papilionidae-Swallowtails and Parnassians (9,000 to 13,000 feet): San Juan Parnassian; Anise, Western Tiger, Two-tailed and Pale Swallowtail. The Pieridae-White and Sulphur-family (9,000 to 13,000 feet): Cabbage Butterfly; Tailed, Ruddy, Veined, Blue, Pine, Checkered, Becker’s and Spring White; Orange, Clouded, Alexandra’s and Scudder’s Sulphur; Large Marble and Sara Orange Tip. The family Lycaenidae, which includes Coppers, Hairstreaks and Blues (9,000 to 13,000 feet): Tailed, Ruddy, Blue, Purplish and Nivalis Copper; Colorado, Coral, Behr’s, California, Banded, Striped, Bramble, Sheridan’s, Gray and Thicket Hairstreak; Marine, Reakirt’s, Western Tailed, Spring Azure, Central, Spalding’s, Silvery, Arrowhead, Northern, Melissa, Greenish, Boisduval’s and Lutz’s Blue. The largest local family, Nymphalidae-brush-footed butterflies(9,000 to 13,500 feet): Carpenter’s, Aphrodite, Nokomis, Callippe, Atlantis, Hesperis, Mormon, Silver-bordered and Freija’s Fritillary; Arachne, Gorgone, Nycteis, Pale, Variable and Edith’s Checkerspot; Northern and Field Crescent; Satyr and Zephyr Anglewing; Riding’s Satyr; Green Comma; Mourning Cloak; Weide-meyer’s Admiral; Ochre Ringlet; Small Wood Nymph; Theano and Common Alpine; Chryxus and Uhler’s Arctic.

A few species, incredibly, spend all of their life cycles between 12,000 and 14,000 feet: Grizzled Skipper, Mead’s Sulphur, Snow’s Copper, Shasta Blue, Rockslide Checkerspot, Chariclea Fritillary, Colorado Alpine, White-Veined Arctic, Melissa Arctic and Magdalena Alpine. Although found at 9,000 feet, the Western White, Arctic Blue and Milbert’s Tortoiseshell are sometimes encountered at 14,000 feet. The sovereign of high-altitude living is the endangered Uncompahgre Fritillary, which lives entirely between 13,000 and 14, 000 feet.

Present only in summer, there are some stray species—generally inhabitants of lower, more arid elevations—that cannot reproduce in the San Juans. When above 9, 000 feet you’ll encounter Dog Face; Cloudless, Mexican and Dainty Sulphur; Variegated Fritillary; Red Admiral; American Lady; West Coast Lady; Monarch; and the high-flying (to 14,000 feet) Painted Lady.

Telluride Visitor Guide