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As a conservation biologist assigned to track rare and declining species, the Oklahoma Natural Heritage Inventory’s Brenda Smith has spent the past six years digging through scant and scattered records, wading through hundreds of roadside patches, and rallying an extended survey team with one goal in mind: assessing the status of Oklahoma’s frosted elfin butterfly populations.  

“It was very daunting at first, wondering if we would be able to find the species or do years of surveys without success. But once we got out in the field, we realized ‘this is doable. We can tackle this.’”  

The target may have been small – frosted elfins have a wingspan of just over an inch and early caterpillars can be as little as a single millimeter – but Smith’s efforts paid off in a big way. 

A small brown butterfly is perched on a piece of grass.
Alex Harmon/CC BY-NC 4.0 DEED

The frosted elfin is a small, grayish brown butterfly that has a dusting of pale-colored scales and short tails on the hindwings.

“Prior to our surveys, there were just a handful of frosted elfin records in the state,” Smith said. “Now, there are 188 records of the species in Oklahoma. We were able to bridge a gap and brought the number of known locations in Oklahoma to 52 sites in nine counties.

“With these records, we were able to reevaluate the frosted elfin’s status in Oklahoma using the NatureServe calculator and adjust the state ranking from an S1 – a species thought to be super rare – to an S3. It’s still a species of concern but is further down the list.” 

This surge of new data comes at an important time for Oklahoma biologists as the U.S. Fish and Wildlife Service is reviewing the frosted elfin’s status across its 25-state range to determine if the species may warrant protection under the Endangered Species Act. Smith was initially contacted about Oklahoma’s frosted elfin populations in 2017 as part of the Service’s Species Status Assessment and the discretionary review is expected in the federal fiscal year 2025.  

From Modest Beginnings… 

When Smith’s search for the frosted elfin began in 2018, all that was known about the butterfly’s status in Oklahoma could be boiled down to a handful of records – nine in total – that were confined to three counties and dated back about three decades.  

Oklahoma’s Brief Frosted Elfin History: 1991 – 2018 

The frosted elfin has only been known in Oklahoma since the early 1990s when entomologist Chuck Harp documented the species in Garvin and Murray counties. The next batch of records followed nearly 20 years later when former USFWS employee Berlin Heck observed the butterfly on his McCurtain County property, more than 140 miles away.  

A small brown butterfly is perched on a twig.
Berlin Heck

This frosted elfin butterfly was documented by Berlin Heck on his McCurtain County property in April 2008. 

Curious if frosted elfins remained at these sites, Bryan Reynolds, another butterfly enthusiast and early member of Smith’s elfin team, conducted follow-up surveys at Harp’s southcentral sites in 2011 and at Heck’s southeastern site in 2018. Though unable to find adult frosted elfins or their larvae at either location, Reynolds searched the surrounding areas and encountered the butterfly at nearby sites. The elfins at the “new” Murray County site have since been dubbed the “Sulphur Colony,” while the elfins at the “new” McCurtain County site are now identified as the “Haworth Colony.”    

This shortage of records initially pointed to a limited population but was also likely a result of the butterfly’s understated appearance and behavior.  

“I often think these butterflies are akin to the birding world’s ‘little brown jobber,’” Smith said. “They’re not showy. They’re not flashy. And they’re skittish. They flit around so much within their host plant patch that it’s hard to get a good look.”   

Adult elfins also have a short flight season that ends before most butterfly enthusiasts start venturing afield.  

“When we first started surveying, the flight season was thought to just be three to four weeks in March and April. In that time frame in Oklahoma, there can be rain, it can be really cold, and there can even be ice storms. Most butterflies just don’t come out that early. But we recently learned frosted elfins can be active in 45-degree temperatures – before the host plant has emerged – which is incredible and surprising.”      

While the butterfly itself is a challenge to find, Smith knew of a trade secret: If a species is secretive or otherwise hard to find, look first for its habitat.   

For the frosted elfin, that meant looking for the known host plant in Oklahoma, yellow wild indigo. In bloom, the indigo’s vivid yellow flowers are hard to miss but its bright green leaves and tendency to grow in clumps make the plant easy to spot from the road even outside of its flowering stage.  

A collage of a woman with binoculars and a clipboard looking at yellow flowers.

Smith’s team targeted clumps of the frosted elfin’s host plant, yellow wild indigo, during the spring butterfly surveys. 

Adult elfins aren’t picky about their nectar source and will feed from a variety of blooms. But the butterflies are a little more particular about where they lay their eggs. In Oklahoma, female frosted elfins primarily seek out yellow wild indigo, Baptisia sphaerocarpa, but Smith’s team also documented elfins using the related Nuttall’s wild indigo, Baptisia nuttalliana, as host plants for their caterpillars. Interestingly, frosted elfin caterpillars found in Oklahoma and the region are bright yellow instead of the green found in other parts of the range.  

A bright yellow caterpillar is on a seed pod.
James Hung/CC BY-NC 4.0 DEED

A yellow frosted elfin caterpillar feeds on a wild indigo plant near Durant, Oklahoma.

While feeding on the wild indigo, frosted elfin caterpillars produce a sugary substance that may foster a connection with ants known as myrmecophily. In some instances, the ants may be persuaded to care for the caterpillar by providing protection, but ants may also attack the elfin’s larvae. Smith’s team documented both sides of this behavior in Oklahoma.  

To find sites where wild indigo has been known to grow in Oklahoma, Smith relied on the Oklahoma Biodiversity Information System as well as museum and public databases and then reached out to the state’s naturalist community to broaden the known indigo sites – and the elfin search radius – to 30 southeastern Oklahoma counties.  

… to More than 150 Records 

Once host plant locations were identified and the logistics of surveying across a wide swath of the state in unpredictable weather conditions were untangled, Smith joined her team of other scientists, conservation groups, and butterfly enthusiasts in the field.    

During the adult butterfly’s flight season, surveyors would walk in a zigzag pattern through indigo patches, documenting any adult elfins that were kicked up. Later, they would return to the patches, examining a minimum number of plants per patch and documenting any frosted elfin larvae found.  

The Oklahoma Frosted Elfin Project has been embraced by a wide range of partners since it began in 2018. Project leader Brenda Smith and managers Marie Stone and Bryan Reynolds conducted the bulk of the surveys along with Dr. Leah Dudley and Jose Montalva of East Central University. Colleagues from the Oklahoma Department of Transportation, Oklahoma Gas & Electric, Oklahoma State University’s Kiamichi Forestry Research Station, Okies for Monarchs, The Nature Conservancy, Bebb Herbarium, U.S. Fish and Wildlife Service, U.S. Forest Service, Chickasaw Nation, Choctaw Nation, Weyerhaeuser, and the Kerr Center for Sustainable Agriculture alerted the team to roadside indigo patches, facilitated searches, and granted access. Oklahoma’s community of naturalists also shared their wild indigo and elfin sightings, and private landowners welcomed the team on their properties and shared their enthusiasm for pollinators.  

In addition to conducting surveys, the East Central University survey team also collected frosted elfin DNA samples as a side project and worked with Hendrix College in Arkansas, multiple learning institutions in Florida, and the University of Massachusetts in an attempt to determine if the subspecies of frosted elfin found in Oklahoma is a separate species.  

“Our main goal was to broadcast out and find as many sites as possible to better understand the frosted elfin’s distribution in the state,” Smith said.  

A map depicting southeastern Oklahoma and the location of survey sites for frosted elfin butterflies.

Smith’s team investigated a number of locations in southeastern Oklahoma and documented frosted elfins at 52 sites in nine counties. 

In addition to increasing the number of Oklahoma frosted elfin records from nine to 188, the survey results also revealed patterns within the state. When looking at a map of documented elfin and indigo sightings, it could be easy to assume more elfins are found in eastern Oklahoma where more triangles appear. But elfins and wild indigo are present in higher densities in southcentral Oklahoma with counts at one indigo patch exceeding 100 individual adult elfins in 2022. Medium numbers of the butterfly and its host plant were found in the northeastern portion of the study area, and the lowest numbers were found at the most southeastern sites where smaller host plant patches were found.  

The health of individual indigo patches and their proximity to other patches were leading factors in calculating the state’s number of elfin populations. Prior to 2018, there were two distinct populations. Now, there are thought to be 10 to 32 separate populations in the state.  

“Every single population is either in the Choctaw Nation or the Chickasaw Nation,” Smith said. “Both Nations will be important partners in conserving this species.” 

Though frosted elfin surveys have ended for the time being, Smith is delighted with the results.  

Not only did the surveys expand the known frosted elfin range in Oklahoma, but Smith was able to build a regional network of landowners, agencies, and volunteers. As a result of this exchange, the Oklahoma Department of Transportation has incorporated conservation mowing practices at known wild indigo sites to reduce the impact to developing frosted elfins; the Oklahoma Turnpike Authority has protected an indigo and elfin site along the Indian Nation Turnpike; and the number of frosted elfin and yellow wild indigo records on the public nature sharing site iNaturalist has increased throughout the region.  

“This is the kind of project you want to be involved in. It gives you hope to know your hard work is paying off and that people are getting the conservation message and want to help.”   

The Oklahoma Frosted Elfin Project was initially funded by the Oklahoma Natural Heritage Inventory and later by the Wildlife Department and U.S. Fish and Wildlife Service through the Cooperative Endangered Species Fund with matching resources provided by the Oklahoma Natural Heritage Inventory in 2021, 2022, and 2023.  

Smith has been a steadfast force at the Oklahoma Natural Heritage Inventory, not only expanding the known range of frosted elfins but also building our understanding of species like the black rail, tiger beetles, and the state’s dragonfly and damselfly community with extensive surveys. Her passion for conservation is especially evident in her recent book, Dragonflies at a Biogeographical Crossroads. After more than 20 years in Oklahoma, Smith has accepted a position with the Nevada Division of Natural Heritage where she will undoubtedly contribute to the knowledge of the Sagebrush State’s natural resources as an entomologist. 

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