EPOD 20th - The Puddling of Butterflies

September 10, 2020

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August 2019 Viewer's ChoiceWe’re celebrating 20 years of Earth Science Picture of the Day during the month of September! Today’s photo features a popular EPOD from the past. Thanks to all of our followers (on the blog, Facebook, Instagram and Twitter) for supporting us. Thanks also to all of you who’ve submitted your photos. We’re most appreciative. This EPOD was originally published August 26, 2019.

Photographer: Patti Weeks 
Summary Author: Patti Weeks 

On a recent trip to the Great Smoky Mountains National Park I took a side trip to the less frequented Cataloochee Valley region on the east side of the park in North Carolina. While elk, reintroduced in 2001, are the area’s main attraction, they were staying cool in the woods beside the open meadows in the middle of this hot summer day. However, much to my delight, the edges of the gravel road were teeming with butterflies, intent on the damp mud.

In my research, I discovered that some Lepidoptera (butterflies and moths) do what’s referred to as puddling or mud-puddling. While I only saw the butterflies near puddles or on damp pebbles, some species can also absorb nutrients from dung and carrion or even sweat on human skin. It’s primarily the males that participate in this behavior in order to ingest salts and amino acids to fortify their sperm, aiding in their reproductive success. The extra nourishment passed to the female ensures egg survival.

I saw three distinct butterfly species: eastern tiger swallowtails (yellow), pipevine swallowtails (dark blue), and the small Appalachian azures (light blue). Thanks to the extensive research of biologist and expert lepidopterist Jeff Pippen, via his website and email confirmation, I was able to narrow his list of nine similar-looking azures (among his list of over 50 blues) to the Appalachian azure.

The kaleidoscope, swarm, or flutter (three of the terms for a collective of butterflies) of each of these three butterfly species was so focused on the puddling activity, that they weren’t at all disturbed by approaching photographers or slowly-moving vehicles. Although each species generally stayed together, they shared some of the same locations. Click here to see a video of fluttering azures above some of the puddling butterflies. Photos taken July 5, 2019.

Photo Details: Top - SONY DSC-HX400V camera; 44.98 mm focal length; f/5; 1/320 second exposure; ISO 80. Bottom - Same except 29.44 mm focal length; f/4.5; 1/200 sec. exposure; ISO 320.