Mormon metalmark: An unmistakable butterfly
Written by:
Linda Kappen
The Mormon metalmark, Apodemia mormo, belongs to a sixth butterfly family, Riodinidae (metalmarks).
The other five families are Hesperiidae (skippers), Papilionidae (parnassians and swallowtails), Pieridae (whites, marbles and sulphurs), Lycaenidae (gossamer wings, with our subfamilies of coppers, hairstreaks and blues) and Nymphalidae (brushfoots).
Riodinidae has around 1,500 species in the Neotropics and about 30 genera in North America. A single species lives in our Pacific Northwest, and a single species is found in Europe. A few species of Riodinidae live in Africa and Asia. With all that being said, it is special to have a single species here in the Pacific Northwest.
The Mormon metalmark reaches a wingspan of 1.25 inches. When looking at the dorsal wing (or open wings), the upper dorsal wing (UDW) background colors range from russet orange to reddish brown to dark brown. On the foreground of the UDW, white spots form angled shapes and patterns with a soft touch of checked white fringes. The antennae are barred in black and white with black tips. The dorsal hind wing (DHW) has white patches against a dark brown background with hints of gray. When the Mormon metalmark perches in a ventral position, white spots stand out on a dark gray background.
Dry areas in the mountains, arid canyons, and flat areas serve as habitat for the Mormon metalmarks. They live in isolated populations and only travel 50 to 60 meters from their group of host plants. Host plants for the Mormon metalmark are buckwheats of the Eriogonum genus.
In the summer months, males appear before females; then the female seeks males on the host plants. Eggs are laid in clusters of up to four eggs. Larvae emerge from protected places during spring and continue feeding on the host plant. The adult’s food is nectar from later summer blooms of composite flowers, such as senecio, rabbitbrush, asters, goldenrod, thistle, and any still-blooming host plants. These butterflies can be seen in flight from late July to early October.
The ranges of the Mormon metalmark in our area of the Pacific Northwest are west of the Cascade Mountains in the Siskiyou and Klamath Mountains, Cascade Siskiyou National Monument, and other mountain ranges in the west to the north, south, and east toward Idaho. It is extraordinary to have one species of Riodinidae in our region.
Uncommon species like the Mormon metalmark also accentuate the importance of preserved lands, both private and public, such as national monuments and national parks. The diversity within these spaces provides undisturbed habitats for any uncommon species living in isolated populations.
A fun fact is that the butterfly was named Mormon by a couple of scientists in 1859 who believed it had come from a Mormon region in Utah. The specimens at the time were actually collected in the nearby state of Nevada. Read more about this name chosen for the Mormon metalmark in the book Butterflies of the Pacific Northwest by Robert Michael Pyle and Caitlin C. LaBar.
Linda Kappen
Image 1: Mormon metalmark on buckwheat. Photo by Linda Kappen.
Image 2: Mormon metalmark on rubber rabbitbrush. Photo by Linda Kappen
