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Entomology (Study of Bugs)/orange/black caterpillar in river


Caterpillar in river
Caterpillar in river  
Last week when I was kayaking on the Multnomah Channel of the Willamette River in Portland, I paddled alongside a small orange/black fuzzy caterpillar with a bit of white fuzz on top and I rescued it -- eventually setting it on the dirt in a planter on my houseboat. Paddling a week later, I saw another caterpillar and rescued it. After five of these, and seeing that none of the caterpillars was dead I figured, silly me, they must belong in the river. I then noticed that about every five feet there was one or more of these caterpillars floating, and seeming to be "eating." I eventually pulled over and put my five "rescued" ones back on land, still hesitant to leave them in the water. I also realized later that I only saw these caterpillars along about one mile of the six I paddled. I was near shore the whole time. I can't find any info about them myself online. Can you help? I would like to add an entry to my blog, My Riverhouse Life, that I will call "The Absurdity of River Caterpillar Rescue."

Hi, Donna:

I think you have the caterpillar of a Ranchaman's Tiger Moth:

I grew up in Oregon and found the adult moths frequently associated with wetlands, so it makes sense the caterpillars would be found in the same situation, though why they were actually in the river is kind of a mystery.  Maybe they blew off the host plant or something.

Please e-mail me with the address of your blog and I'll check it out.  I run "Bug Eric" blog, though lately I've been uninspired given the unseasonably cold spring we've had so far in Colorado....


Entomology (Study of Bugs)

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Eric R. Eaton


I answer insect and spider identification questions ONLY. Attach images if possible. No "what bit me?", "what do I feed this bug in captivity?", or science fair project questions please. NO TECHNICAL QUESTIONS ABOUT INSECT PHYSIOLOGY.


Principal author, Kaufman Field Guide to Insects of North America. Professional entomologist employed previously at University of Massachusetts, Chase Studio, Inc., and Cincinnati Zoo; contract work for West Virginia Department of Natural Resources, Smithsonian Institution, and Portland (Oregon) State University.

Author, Kaufman Field Guide to Insects of North America, Missouri Conservationist magazine, Ranger Rick, Birds & Blooms, Timeline (journal of the Ohio Historical Society). I have contributed to several books as well.

Oregon State University, undergraduate major in entomology, did not receive degree.

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One of the top 50 experts in all categories for, 2009.

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Principal author of the Kaufman Field Guide to Insects of North America, Smithsonian Institution (contract), Cincinnati Zoo (employer), Portland State University (contract), Chase Studio, Inc (employer), Arkansas Museum of Discovery (guest speaker). Currently seeking speaking engagements, leadership roles at nature festivals, workshops, and ecotours.

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