Field Notes: In Search of Buck Moth Caterpillars …

This Field Note is by Joe Brehm, Rural Action Environmental Education Director.

Four to five months from now, if you are lucky, you may find yourself ambling along a wooded ridgetop under a clear blue autumn sky while big golden hickory leaves float down through the thinning canopy. If you are even luckier, you may see a conspicuous black and white insect with a splash of reddish orange fly across your face at a high rate of speed, soaring through the bright forest with urgency. The stark soaring insect, of course, is the buck moth (Hemileuca maia), a member of the giant silkworm moth family (Saturniidae) that also includes the more famous luna moth (Actias luna).

I recently had the chance to meet and speak with buck moth researcher Jim Tuttle, author of The Hawk Moths of North America, who was visiting Ohio in search of buck moth caterpillars. He and other researchers have some evidence indicating that glaciation induced a significant change in buck moths, potentially resulting in two different species. Buck moth caterpillars in the unglaciated portion of eastern North America – including Southeast Ohio – feed on oak leaves. Caterpillars in glaciated northwestern Ohio, however, feed on willow and cottonwood leaves. Despite looking identical, the populations from the two regions do not recognize each other’s pheromones. Jim and his collaborators at the University of Kentucky plan to collect caterpillars from glaciated and unglaciated areas, let them pupate and metamorphose into adult moths, and test their DNA and the composition of their sexual pheromones.

Jim is looking for assistance from citizen scientists in our area to search for buck moth caterpillars, which by mid-June can be found crawling across the forest floor in search of a place to burrow into the soil and form a cocoon. If you come across one of these wandering buck moth cats, you can carefully collect the caterpillar in a breathable jar and make sure it has plenty of soil and leaf litter, and promptly email me at joe@ruralaction.org so that we can make arrangements to get the caterpillar to Jim. Please be very careful with the caterpillars, which are known to cause a painful sting, and wear gloves if handling them.

Becoming enamored with buck moths was quite effortless after my favorite naturalist, Paul Knoop, taught me about them years ago. He was able to identify the black and white blur that had just zipped through the woods. The males can detect female pheromones from great distances and fly to them with striking purpose; Jim only somewhat facetiously recommended wearing a helmet if a captive female buck moth has recently hatched. Males will come zooming in without regard for mere humans. Seeing buck moths fly through an Appalachian forest in the peak of fall is one of the great spectacles of the season, leaving me with the same feeling as watching a big whitetail work on a rub or a marbled salamander bound for a vernal pool. Thanks to Jim for giving us an opportunity to collaborate on this interesting project, and providing an excuse to get out in the woods and search for caterpillars.

(Field Notes is an occasional series that takes readers into local forests to learn about our natural world. Become a citizen scientist and join the more than 475 volunteers who have contributed close to 16,000 observations via iNaturalist to our “bioblitz” of the WNF’s Athens Unit, documenting roughly 3,400 species of plants, insects, fungi, mammals, birds, and more. You can join us by following instructions here.)