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Eastern Black Swallowtail caterpillar

Papilio polyxenes


The Black Swallowtail caterpillar has an orange "forked gland", called the osmeterium. When in danger the osmeterium, which looks like a snake's tongue, everts and releases a foul smell to repel predators, as seen in second photo.


found this eating parsley


I spotted this in the Fragrance garden beside the Floral Showhouse on the Niagara Parkway. There were at least 3 of these caterpillars eating the parsley.

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Dan Doucette
Dan Doucette 10 years ago

Thanks kat for the information. I didn't know the smell would be of what they were eating but it makes sense.

kat.herbalmedicine 10 years ago

When the osmeterium sticks out you can smell the plant that they have been eating. They feed on fennel ( smell like licorice), wild carrot ( carrots of course) and dill ( these smell like pickles). It may be part of a defense mechanism.

Dan Doucette
Dan Doucette 10 years ago


KarenL 10 years ago

Cool pic!

Dan Doucette
Dan Doucette 10 years ago

Thank you.

alaynahuter 10 years ago

Great color!

Dan Doucette
Spotted by
Dan Doucette

Niagara Falls, Ontario, Ontario, Canada

Spotted on Aug 9, 2011
Submitted on Aug 10, 2011

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