Ruby Spotted Swallowtail Caterpillar Aggregation from Mexico

Bugs chilling in a circle on a tree
Location: Chichen Itza, Mexico (2hrs from Cancun)
November 7, 2010 5:16 pm
I am really curious to learn what these bugs are. I was at the ruins of Chichen Itza in Mexico and I saw them on a tree. We took video of them because they would react to noise by twitching slightly. I am sending a still from that video. Let me know if you want me to send it also.
Signature: Jessika Canizalez

Ruby Spotted Swallowtail Caterpillar Aggregation

Hi Jessica,
Many Caterpillars, and indeed a goodly number of tropical Caterpillars, for aggregations because there is safety in numbers.  We do not recognize this species, but their social formation is intriguing.  Many
Morpho Butterflies have caterpillars that form aggregations.  We may try to contact Keith Wolfe who has identified several Morpho species for us in the past.  We hope to be able to provide you with a species identification soon.

Update from David Gracer
Caterpillar Aggregation from Honduras: Arsenura armida”
A.armida: very edible!
I tried this species in 4/10 at an international conference on entomophagy; one of the presenters had brought them from Mexico, and said that they’re farmed in the southern part of the country.  Fascinating.
They were also exceedingly tasty, if rather unusual.  They were fried or rather sauteed, and tasted like a cross between bacon and jerky.  Quite yummy, actually.

Thanks for the edibility update Dave.  We located a photo of the adult Arsenura armida on God of Insects and learned it is a Giant Silkmoth.  We have posted other images of Arsenura armida in the past, though the coloration seemed different and we never received images of this circular “stage coach” defense.

Correction Courtesy of Karl
November 8, 2010
Hi Daniel and Jessika:
I believe your caterpillars are Ruby-spotted Swallowtails (Papilio (=Heraclides) anchisiades idaeus), a species that ranges from Texas to northern South America (or Argentina, depending on the source you read). I found a cluster just like this in Belize in 2007, but was unable to identify the species. It was during my search for an ID that I came across your fabulous WTB site, and I have been addicted ever since. Somewhat ironically, my first submission to WTB was an ID request for this very creature, but my submission was unfortunately lost in your avalanche of email. Compare this photo to a nearly identical one that appeared in Jim Conrad’s Naturalist Newsletter, with identification by social caterpillar specialist Dr. Terrence Fitzgerald. You can check out the Butterflies of America website for pictures of adults and other life stages. Regarding the caterpillars I saw in Belize, I was able to observe them over a five-day period and was struck by their tenacious site fidelity. They spent every day gathered at the exact same spot, low to the ground on the sunny side of a tree trunk. Then every night they disappeared, presumably into the treetop somewhere, but I was never able to find them there. I somehow managed to miss the actual processions, which would have been the really interesting part. When I passed my hand close to them they would raise their heads and wave them vigorously side to side, a gesture no doubt intended to intimidate me. Regards.  Karl

Confirmation from Keith Wolfe
NOvember 8, 2010
Daniel, assuming their good fortune continues, this molting aggregation of caterpillars (chillin’ almost certainly on a rutaceous tree) will metamorphose NOT into moths or morphos, but rather Papilio anchisiades or something very closely related.  Here is the same gregarious swallowtail species from the same famous Mayan site . . . (click the link under “Amazing caterpillar picture”*)
. . . and a lesser number of cohorts from elsewhere: (the progeny of at least two females)
Best wishes,
* In my experience, P. anchisiades larvae are not processionary.

Photo of author


BugMan aka Daniel Marlos has been identifying bugs since 1999. is his passion project and it has helped millions of readers identify the bug that has been bugging them for over two decades. You can reach out to him through our Contact Page.

1 thought on “Ruby Spotted Swallowtail Caterpillar Aggregation from Mexico”

  1. What upper-midwest (Missouri) moths/butterflies would aggregate like this? I’ve found them from time to time –but none since I’d become a potential predator. The ruby-spotted swallowtail is one I’d not seen before.


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