Mendon Meadow: Refuge for the Rare

From the road, Mendon Meadow looks like a typical hay field in Cache Valley, but this small acreage is anything but typical. Fireflies flicker across the fields after dark in June and early July, and an active breeding population of Silver-bordered fritillaries can be seen nectaring on clover, goldenrod, Joe-Pye weed, and other native plants that line the borders of the field. Viceroy butterflies flit through the willows laying eggs, while Monarch butterflies swoop and glide gracefully in search of milkweed plants. By late July, the blooms of the Ute Lady’s Tresses (Spiranthes diluvialis) orchids dot the field.

A common wood nymph harvests nectar from a Ute Ladies'- Tresses bloom. Photo by Miriam Valere, BRLC Board Member

Lepidopterist Todd Stout and Rare Insect Research Technician Rachel Irvin from Utah State University took a site tour of Mendon Meadow with board member Miriam Valere to look for a critically imperiled butterfly: the Utah Wood-nymph (Cercyonis pegala utahensis). They both were excited to see several Utah Wood-nymphs along with Common Wood-nymphs (Cercyonis pegala paludum) on wing that day. Todd explained that there are many subspecies of the Common Wood-nymph, and that the Mendon population appears to be a blend between the Common Wood-nymph and the Utah Wood-nymph.

Photos by Miriam Valere, BRLC Board Member

After seeing Mendon Meadow, Todd shared these thoughts:

I applaud and feel it is justified for the Bear River Land Conservancy to commit resources to retain the natural habitat of Mendon Meadow as it, in addition to native and sensitive flora already monitored, also harbors populations of the sensitive silver bordered fritillary (Boloria myrina tollandensis) which exclusively uses the wetland species Northern bog violet (Viola nephrophylla) and the critically imperiled Utah Wood-nymphs (Cercyonis pegala nr. utahensis). I’m actually more concerned with the welfare of the Utah Wood-nymphs as populations that used to exist in ag farms in Utah and Salt Lake Counties are either too fragmented to locate or are extirpated altogether. Much of its wet meadow habitat near valley rivers that was private property has been converted to commercial property; thus destroying the habitat and eliminating populations of this butterfly. – Todd Stout

Rachel Irvin added:

Protected sites like Mendon Meadow are vital for filling gaps in rare insect conservation management data through ecological monitoring. With two rare butterfly species for the state of Utah present at this location, identifying factors such as plant assemblages, hydrologic dynamics, the presence of other insects, and the effects of haying and cattle grazing will be extremely valuable in understanding which management actions support ideal habitat conditions. - Rachel Irvin, Rare Insect Research Technician, Quinney College of Natural Resources, Wildland Resources Department, Utah State University