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Black Swallowtail Caterpillar

Papilio polyxenes


When provoked, the larvae of this species sprout eversible orange horns called osmeterium, which release a foul odor in order to deter predators. The osmeterium is a defensive, glandular organ that is coated in stinky chemicals, and is located at the base of the caterpillar's head (see photo 4 for slit that osmeterium pops out of). The osmeterial odor changes between species and within the life stages of the caterpillars. This particular caterpillar's osmeterium smelled like rancid citrus. The larvae of this species changes color quite dramatically with each molt. This caterpillar was mostly black with white stripes and yellow dots.


I spotted this caterpillar on fennel (Foeniculum vulgare) in a rural garden.


Spotting #1,000!

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maplemoth662 5 years ago

Your welcome, Christine....

Christine Y.
Christine Y. 5 years ago

Thanks maplemoth :)

maplemoth662 5 years ago

Six, very beautiful photos....a very beautiful caterpillar....

Christine Y.
Christine Y. 5 years ago

Thanks Mark!

Mark Ridgway
Mark Ridgway 5 years ago

Congrats on 1k !!

Christine Y.
Christine Y. 5 years ago

Thanks! It was a very beautiful, yet incredibly stinky "king" ;)

flowntheloop 5 years ago

Gorgeous! It looks like a king (with a little crown)!

Christine Y.
Spotted by
Christine Y.

Connecticut, USA

Spotted on Nov 3, 2017
Submitted on Nov 4, 2017

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