Owlfly Larvae in Phalanx Formation


A few months ago I wrote a post about an owlfly (Ascalaphidae: Suhpalacsa sp.) laying eggs in a spiral. Today I was lucky to observe the newly-eclosed 1st instar larvae in full typical defensive formation. The first thought that came to mind was mimicry of a plant-like structure, as I’ve seen with incredible medusa-like aggregations of Heliconius doris in Peru. However, it likely serves another purpose. Like antlions, owlfly larvae are voracious predators equipped with large scythed mandibles to clasp prey and inject tissue-dissolving enzymes before consumption. The phalanx formation is an effective deterrent to any insects that could take out a single owlfly larva, much like in the Hellenistic world. It would be amazing to watch the owlflies hatch and take up the arrangement. Imagine the larvae eclosing one by one and each taking its rightful position in the conical mass of jaws.


The larvae were each 2.5 millimeters in length, and without my macro setup I struggled in the blinding sunlight. I had seen countless pictures of the behavior but had never observed it myself. Definitely a tick off my list of entomological life goals. I returned tonight to check up on my new acquaintances (it wasn’t easy locating a single 2cm long cluster in the shoulder-high spear grass), and about 75% of them had left the cluster. By tomorrow morning the remaining larvae should be dispersed, having become independent terrestrial ambush hunters.

Photographed in situ [1]


See my older post about an adult Suhpalacsa owlfly laying eggs here.

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