Leona's Little Blue

We have an endemic butterfly species in Klamath County, Oregon. Leona's Little Blue (Philotiella leona) is only known to occur in a small area (12.8 square miles) near Sand Creek. A related species (Philotiella speciosa, the Small Blue) occurs in scattered populations in California and the Southwest.

This is a tiny butterfly. Adults are on the wing in late June and early July of most years. An inconspicuous plant (Eriogonum spergulinum, spurry buckwheat) is the known food plant for the larvae. Butterfly species often specialize when it comes to larval food plants--while adult Monarchs will take nectar from many types of flowers, the caterpillars need milkweed (genus Asclepias, not some of the other plants that are colloquially called milkweeds). Similarly, Leona's Little Blue may be seen on a variety of flowers in its habitat including other buckwheats, willowherbs and borages, but when the females lay their eggs they lay them on spurry buckwheat. 

I first sought out Leona's Little Blue back in 2012, on a hot 4th of July. After a bit of searching, I found them readily enough, and got some photos including one of a female ovipositing (egg-laying). 

This Leona's Little Blue butterfly laid a tiny white egg in the flower head.

Most butterfly populations fluctuate from year to year with weather and habitat conditions. Some populations even die out, perhaps eventually to be replaced by colonizers from nearby populations. Because there is only one known population of Leona's Little Blue, this species is likely to be extra-vulnerable to threatening events. The main threats seem to be wildfires (a small fire might open up new buckwheat habitat, but a large one running through the area might scorch everything including the butterflies in any life stage) and pesticides (if pesticides are sprayed on surrounding land to control insects, they may drift into the butterfly's range and kill larvae). Since the butterflies and their host plants thrive in clearings, overly dense stands of lodgepole pine also limit available habitat. Just a year after I visited, the Military Fire burned just north of the known range of Leona's Little Blue. I heard one report a few years ago from some butterfliers who had found Leona's Little Blue, but in fewer numbers than in 2012.

The Xerces Society filed a petition to list Leona's Little Blue under the Endangered Species Act due to its restricted population and potential threats to its continued survival. The US Fish and Wildlife Service found that listing wasn't warranted. It's really a complex issue. The butterfly is extremely vulnerable to catastrophic events and changes, but some commercial forestry operations or prescribed fires might be beneficial in creating habitat.

For some reason, I didn't stop in the habitat again until 2022. Most of the habitat is privately owned, but most of that isn't posted against entry. Leona's Little Blue was originally collected by Harold Rice and his wife Leona just off US Highway 97 at milepost 226 (see paratype specimens at Butterflies of America), and the boundaries of its range are considered milepost 225 to 230. Once you know what to look for as far as habitat, it's relatively easy to find the butterflies during their flight season. My favorite place is a seldom-used dirt road/trail with spurry buckwheat and other plants growing in the middle of the road while the wheel ruts remain unvegetated. It's possible to walk in the ruts without fear of trampling butterfly plants while having access to photograph butterflies in the center or on the sides of the road. I'm happy to report that on July 8, 2022 I was able to find a decent number of Leona's Little Blues in a few short sorties along this road. 

Finding the butterflies is one thing. As already mentioned, they are tiny--significantly smaller than more common blue butterflies of our region such as the Echo Azure and Boisduval's Blue. Photographing them is another. When in flight, they fly in a very fast, low, zigzagging pattern that makes me dizzy trying to follow them. When they alight, sometimes they do so briefly. On this trip, I saw males drop down to bare sand and immediately fly back up. If they were getting minerals from the sand, they were doing so very quickly. Most of the butterflies I saw in 2022 appeared to be males (more blue on the dorsal surfaces of the wings). I saw one apparent male-female encounter; the male chased the female, but the female left and decided to nectar on some sulphur buckwheat. I was also on my way to an event, but I ended up with a few decent photos.

A frontal view showing blue on the dorsal surfaces of the wings

On a sulphur buckwheat

On a sulphur buckwheat with wings open

Look at that proboscis!

Sans flash for the purists and to give a more 3D perspective

To me, Leona's Little Blue is one of those unobtrusive wonders of nature. It persisted in its little area of the world until the mid-1990's before even being noticed, and it persists still. I'm glad to have seen it.

For more information:

Population Biology and Behavior of the Imperiled Philotiella leona (Lycaenidae) in South Central Oregon (2014)

Xerces Society for Invertebrate Conservation

Butterflies of the Pacific Northwest by Robert Michael Pyle and Caitlin C Labar (link to purchase on bookshop.org). The most current field guide to our butterflies.