In last week’s episode, we met cryptic phasmatids in Costa Rica using the clever defense of mimicking a stick to avoid detection by rainforest predators. Let’s jump on a plane and head about 3,000 miles south to the base of the Villarrica volcano near Pucon, Chile. In a Jurassic Park-like setting, ancient Gondwanian trees such as Nothofagus and Araucaria cling to hillsides. Here along a rushing river at the base of the volcano we discovered the giant phasmatid, locally known as the chinchemolle, unabashedly grazing on clover and other herbaceous plants lining the stream bank.
Unlike its cryptic Costa Rican cousin, this monster of the insect world does not attempt to hide from its predators. Oh no, just the opposite. These gaudy herbivores visually warn their enemies not to mess with them lest they risk a nasty experience. The striking adult male elegant walking stick bedazzles onlookers with brilliant scarlet bands encircling its jet black body. White splotches at the leg joints complete a “look” designed to catch a vertebrate’s attention. The female chinchemolle, while more subtly adorned, is also striking in appearance with her army-green body ringed with orange bands.
While most other members of the walking stick clan try to avoid predators by mimicking plant parts and moving very slowly, these brightly colored active ground dwellers have another trick up their sleeve, or should we say behind their head? The first segment of the thorax bears two openings leading to large secretory glands just beneath the exoskeleton of the insect. These glands produce a highly irritating, noxious ketone that can be squirted into the face of an attacking bird, lizard, or mammal. In fact, there are reports of serious eye injury to humans who looked just a little too closely and were rewarded with a squirt in the face by the chinchemolle’s Floridian cousin, the two-striped walking stick we met in a previous episode. One scientific report declares that local residents of Chile know better than to challenge the chinchemolle to a stare-down, lest they risk the peril of pain and temporary blindness. However, a Bug Guy from North American could not resist handling the chinchemolle and when I stared into the eye of the large phasmatid, it only stared back. If I wasn’t certain that insects lack eyelids, I could have sworn that it gave me a wink.
Whether it’s a dash on a riverbank or dining on tender leaves, striking coloration of the male chinchemolle warns predators not to mess with him. Notice the opening to the secretory gland just behind its head. This is where defense fluid discharges.
Bug of the Week thanks Dr. Audrey Grez of the University of Chile for identifying the chinchemolle and providing the inspiration for this episode. The following references were used in preparation of this episode: “4-Methyl-1-hepten-3-one, the Defensive Compound from Agathemera elegans (Philippi) (Phasmatidae) Insecta” by Guillermo Schmeda-Hirschmann, and “Defensive spray of a phasmid insect” by Thomas Eisner.