Big “Cat” Hunters

Tall Timbers Develops a New Tool for the Conservation of a Rare Species

In an age of rapid species decline, wildlife biologists must develop ways of re-establishing species to areas where they have gone extinct. Wildlife reintroductions are an increasingly necessary tool for maintaining our natural species diversity. The Stoddard Bird Lab specializes in this technique and has spearheaded successful reintroductions of red-cockaded woodpeckers and brown-headed nuthatches. But can we do it with a rare butterfly?

An adult frosted elfin butterfly. Adults are about 1” tall.

To answer this question, Dave McElveen and I, Tall Timbers researchers, are studying the life history of the rare frosted elfin, a fire-dependent butterfly of sandhills longleaf pine ecosystems. The elfin has been extirpated from large portions of its range in the eastern US, but our local population in the Apalachicola National Forest (ANF) is healthy. This gives us an opportunity to work with elfins without much risk of harming the population. Re-introduction has never been done for frosted elfins, but we set out to learn the if and the how.

Butterflies have four life stages: egg, caterpillar (“cat”), pupa, and adult. For elfins, we thought relocating caterpillars had the best chance of success with the least impact on the “donor” population. Specifically, moving older, larger caterpillars that are just a few days from becoming pupae. This way, the cats were free to choose where they wanted to spend the next nine months as a pupa instead of us deciding for them.

Frosted elfin caterpillars grow to about ¾” in length


Frosted elfin caterpillars are well camouflaged when feeding on their host plant, sundial lupine.

But how could we keep track of our relocated cats among all the undergrowth and from among all the other cats present? We needed a way to unequivocally identify them. The answer: hot pink fluorescent powder! The powder has been proven safe for caterpillars and is environmentally friendly. So, we gave it a try.

We powdered and relocated 20 cats from 3 different sites within the ANF. We checked on them for 6 days during the day and at night. Much to our delight they fed and developed normally. Also, they retained a lot of their powder even when rained upon. We were even able to follow 3 to their pupation sites thanks to the powder trail they left! This is only the second time pupation sites have been recorded for this species.

Putting fluorescent powder on a caterpillar.


Rob using UV flashlight and glasses at night to spot powdered caterpillars.


Two ¾” frosted elfin caterpillars under UV light at night: with fluorescent powder(left) and without (right).

Our translocation worked well but much more remains to be understood about how to restore habitat conditions for the elfin before we can return them to where they once were. For now, at least, we have a new tool ready for the next big move in the long-term conservation of this species.

Journey of a frosted elfin caterpillar from its last feeding site (on left) to pupation site (on right).


Powdered caterpillar beginning to pupate in soil.


Frosted elfin pupa (~3/4” long). Frosted elfins spend 9 months of their life in this stage as they transform into an adult.

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