What's That Bug? does not endorse extermination
Swallowtail Caterpillar Aggregation

Swallowtail Caterpillar Aggregation

Subject: Caterpillar orgy
Location: Antigua, Guatemala
October 13, 2014 8:40 am
Hey Bugman,
I was planting a bunch of ginger in my garden here in Antigua, Guatemala yesterday and noticed an odd discoloration on the base of my lime tree.
When I went in a bit closer I realized it was about three dozen of these caterpillars, who decided to crop dust me en masse with their osmeterium (or as I prefer to call them, Angry Caterpillar Fart Getaway Tubes®.)
What gives? Did the Caligula of caterpillars suddenly move in, or is this some kind of protective herd behavior against predators?
Also, any help in identifying these little hedonists would be appreciated.
Thanks!
Signature: Ornery Regarding Gassy Youths

Swallowtail Caterpillar Aggregation

Swallowtail Caterpillar Aggregation

Dear Ornery,
These sure look like Ruby Spotted Swallowtail Caterpillars to us, a species in which the caterpillars are social, often being found in large aggregations.
  According to the Butterflies and Moths of North America, the caterpillars of the Ruby Spotted Swallowtail, Papilio anchisiades, feed on the leaves of:  “Trees in the citrus (Rutaceae) family including Citrus, Casimiroa, and Zanthoxylum species” and “Caterpillars rest in clusters on host plant during the day and feed at night; they all feed and molt at the same time.”  This communal activity must have some survival benefit for the species, and the group effect of the olfactory defense mechanism must be more effective than the smell produced by a single individual.  The adult Ruby Spotted Swallowtail is a pretty butterfly.

Thanks so much for the rapid reply! The Ruby Spotted Swallowtail is indeed quite beautiful. I have been a big fan of WTB for years and it has helped me identify dozens of critters. Keep up the great work.

What's That Bug? does not endorse extermination
Location: Antigua, Guatemala

Leave a Reply

Your email address will not be published. Required fields are marked *