A Conversation with Dr. Jeffrey Miller, Ecologist, Professor Emeritus, Author, and Dedicated Mapper

By Erin Keller and Kristina Lefever, with assist from Dr. Miller

On May 20, 2023, Dr. Jeffrey Miller visited Southern Oregon at the invitation of Pollinator Project Rogue Valley (PPRV) to speak about his ongoing project mapping butterflies in Oregon. After the presentation, Erin was fortunate to talk with him about three topics: the need for and benefits of mapping butterflies in Oregon, factors that impact butterfly populations, and two innovative ways that we all can be involved.

Dr. Miller’s mapping project is an enormous undertaking that spans multiple decades, beginning with the efforts of John Hinchliff, who collected records of Oregon butterfly sightings and locations, dating back to the early 1900s.

In 1994, after hearing Hinchliff present his data, Dr. Miller proposed digitizing the records. Hinchliff agreed, and turned over his 27,000 records, (of which, 17,000 were unique locations.) It would take Miller and a student, Dana Ross, FIVE YEARS to enter and proof the records, which included the butterfly species, its location, and host plant(s,) into an OSU database. Unbelievably, during a departmental transition, those data were later lost! Now retired, Miller is painstakingly re-creating the data, while adding more recent sightings, in order to create a series of maps for each butterfly species recorded in Oregon. Currently, he has records of 35,000 unique sighting locations.

Oh my, what fascinating and important information these maps provide! As an ecologist, Dr. Miller looks at patterns of distribution. By mapping each species and subspecies, he can notice patterns of “clumping and voids” in the distribution for a given butterfly species, or for many butterfly species.

Mapped sightings of two subspecies of the Golden Hairstreak butterfly (Habrodais grunus). Dorsal and ventral sides of H. grunus lorquini below.

From there, he can consider questions, such as the following: what factors limit butterfly distribution, such as temperature, food source, and habitat fragmentation? How sensitive is the habitat distribution to loss by agriculture, housing development, clear-cutting, and invasive plants, such as blackberries? Are all butterfly species limited in range to the range of its host plant(s)? What happens to the butterfly population when the host plant’s range shrinks or disappears??

An important factor in considering butterfly habitat loss is that many butterfly species “specialize,” meaning they need a particular plant genus or species for their young (caterpillars) to feed on. Miller tells us that half of the 173 species of butterflies in Oregon specialize to only one genus of plant. The Oregon Swallowtail caterpillars take this further, and can only feed on one species of plant within the genus Artemisia. Of the remaining half who can feed on plants from more than one genus, most cannot range beyond one particular family of plants.

Record of number of lepidoptera species found when "beating" a tree or shrub to make the insects drop on a cloth.

This “host–to-caterpillar” relationship is due to the million-year evolutionary partnership of plants and lepidoptera. Plants have evolved to avoid being eaten. For instance, milkweed sap contains the chemical cardiac glycoside, which is toxic to most caterpillars (and other herbivores). The monarch has adapted to ingest this chemical, and then sequester it within its body, rather than digesting it. This makes it possible for the caterpillars to feed on the milkweed leaves, when other herbivores could not. Other caterpillars evolved to be able to eat other plants – some more specific than others. For instance, the great spangled fritillary caterpillar can eat only native violets!

More monitoring is needed as climates and habitats change – keeping in mind that monitoring butterflies is far from an automated process, as it requires a (knowledgeable) human to be present for each sighting.

This leads us to Dr. Miller’s first suggestion for how we can be involved: Adopt a site. What does this mean? Choose your favorite local outdoor location, and make it your “project location” for a season, or for multiple seasons. Monitor the butterflies at your special place, every two weeks from late April through July or early August.

If you use iNaturalist, you can join the “Butterflies of Oregon's Project,” which is administrated by Neil Bjorklund, and your photos will be included in this impressive citizen science list. Per Bjorkland, “we just surpassed 23,000 butterfly sightings in Oregon!” (May, 2023) You can also follow Neil Bjorklund’s "butterfliesoforegon” site, which has only Bjorklund’s sightings.

Make your monitoring project fun! And know that you are contributing to an important body of knowledge.

A second suggestion will sound familiar, but Miller adds a fun twist. Create a wildlife food web in your yard or garden. Dr. Miller suggested three garden plants that are hosts to multiple butterfly species: lupine, violets, and buckwheat (especially sulphurflower buckwheat / Eriogonum umbellatum.) Per Miller, “lots of butterflies want the nectar, lots of caterpillars want the leaves, and birds want the caterpillars. Then, sit back and watch the wildlife!”

He adds – the more you can plant, the better. A 20’ X 20’ plot would be small. However, if you can only plant one plant, then plant one plant. It all helps. And I’ll add – ask your neighbor to plant one plant!

It was a true pleasure to speak with Dr. Miller, and a challenge to limit this post to the content above, as he provided so much information. If you have an opportunity to hear him speak, we urge you to accept. Learn more from Dr. Miller’s publication, “Butterflies and Moths of the Pacific Northwest Forests and Woodlands; Rare, Endangered and Management Sensitive Species” (2007.)

Oh, and don’t forget to plant that one (native) plant to feed the caterpillars. Dr. Miller has put-together an awesome list of resources here for butterflies and moths in the Pacific Northwest. And please visit the Resources on our website to find other resources about pollinators, plants, and gardens.

About Jeffrey: After a couple of years of indecision while attending three Universities and taking classes to satisfy requirements for five different majors (in sequence!), Jeffrey found his niche in Entomology at UC Davis with a BS degree in 1973. After receiving his PhD in 1977, he was offered a Post-Doctoral position. Planning to stay at Davis as an Instructor, his first term was cut short by an appointment to Assistant Professor at OSU in 1979. Retiring 36 years later, in 2015, Jeffrey realizes that his primary charge throughout has been caterpillars. Jeffrey has authored a number of important reference books and an amazing article about insects in Oregon Flora, vol. 2 (not available in the online version).