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Larva & Pupa Black Swallowtail

Papilio polyxenes


The larva was found walking on the ground in a garden on 24 December 2013. I brought it home and gave it a stick and it began to prepare for pupation on 26 December. It attached its caudal prolegs to the stick with silk and built it's silk safety line (attached to each side of the body between the true legs and the first prolegs and attached to the stick at a single point in front of the body) See picture 4. The larva began it's prepupal shrinking once these tasks were finished. It moved and convulsed a great deal in the next 3 days and certainly needed its safety line to stay in place. The larval skin was shed off of the formed pupa on 29 December (pictures 5 and 6) and remained in a clump at the tail end of the body. I can't imagine how the skin is shed past the safety line with the line then remaining attached to the pupal surface. The whole process is a miracle and doesn't look like it is a pleasant experience. How in just 3 days can the pupal skin emerge completely delineated with the adult body parts of legs, wings, mouthparts and antennae which are not yet formed inside of the pupa? Now it is time to wait. Picture 5 shows side and top views of the newly formed Pupa (29Dec13). Picture 6 shows side and top views of the same pupa 20 days later (17Jan14). The pupa has darkened considerably and would be more camouflaged now on its host plant.


Urban area, San Cristobal de Las Casas, 2,200 meters.


The caterpillars of this species have a small yellow-orange osmeterium, a defensive structure in the dorsal prothorax that can be everted when threatened. This organ produces foul smelling pheromones. I tried to get my larva to evert its osmeterium for a picture, but it just would not do it. Not even with my scariest Halloween mask :) However, you can see it here: This link shows the adult butterfly: This link shows the egg and larvae:

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LaurenZarate 6 years ago

Thank you kd, the details that appear on the pupa are fascinating, since they are visible on the outside long before they finish forming on the inside!

kdpicturemaker 6 years ago

Pupal stage is amazing - you can see the wings and other details as the subject changes dramatically from one form to another.

LaurenZarate 6 years ago

Added a photo showing the camouflaged coloration of the pupa after 20 days.

LaurenZarate 6 years ago

Thank you kd, the pupa is changing and is darker, with blotches and more camouflaged. I'll add a picture. Still waiting for an emergence!

kdpicturemaker 6 years ago

Fascinating at every stage.

LaurenZarate 6 years ago

Thanks Albert :)

AlbertKang 6 years ago

Very nice serie of pictures :)

LaurenZarate 6 years ago

Ha ha ha, thanks Mark. Actually, I think I'm scarier with no mask at all….

Mark Ridgway
Mark Ridgway 6 years ago

Stunning cat and good set of pics too. Get a new halloween mask :)

LaurenZarate 6 years ago

Thank you so much Jemma and Luis :)

Hema 6 years ago

Such a beautiful spot.

LuisStevens 6 years ago

Beautiful caterpillar and wonderful comments Luaren!

Spotted by

Chiapas, Mexico

Spotted on Dec 29, 2013
Submitted on Jan 5, 2014

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