Field Notes

Most animals have a fundamentally different experience of the world than we do, so the possibility of friendship between insects is a difficult thing to judge.

I think we can safely rule out friendship between cicadas and all the species of wasps that want to eat them. That still leaves tens of thousands of species of wasps that have no direct ecological relationship with cicadas, in what we will call the "kind of maybe plausible friendship zone". I think their friendship might go something like this:

Earlier this year (April/May), I had the pleasure of drawing the life cycle of Megarhyssa atrata for this paper.

I want to personally thank the authors for giving me this amazing opportunity. I had a blast drawing these! I tried my hardest to create some quality illustrations. 🙈

https://www.researchgate.net/figure/Life-cycle-of-the-woodboring-idiobiont-ectoparasitoid-Megarhyssa-atrata-Fabricius_fig1_384466437

Dragonfly nymphs have a bizarre anatomical feature -- their lower jaw is equipped with an arm-like apparatus that can swiftly expand and retract, allowing the nymph to grab and devour its prey.

This apparatus is known as a prehensile labial mask. It consists of two long structures that pivot around a multiaxial joint, a pair of labial palps, and movable claws that are used for gripping and chewing. When the labial mask is not in use, it simply folds up beneath the nymph's head.

According to this article:

In their biotopes, dragonfly and damselfly larvae are important predators that catch their prey with a biomechanically unique and highly efficient catching apparatus known as the prehensile labial mask, which is formed by the modified labium.

By means of this prehensile mask, the larvae can capture fast-moving organisms up to their own size. The movable hooks, pointed lobes at the end of the prehensile mask, grab or often pierce the prey to hold it tight.

Dragonfly nymphs live in ponds, lakes, and other freshwater ecosystems, where they prey on other invertebrates, tadpoles, newts, and even small fish.

The nymph lies in wait, using its remarkable eyesight and sensitive mechanoreceptors to detect potential prey; once a victim is in range, it engages the labial mask, which can fully extend in just 15 milliseconds. The claws at the end of the labium then draw the victim toward the serrated mandibles of the nymph's mouth.

For decades, researchers believed that the movements of the labial mask were powered by hydraulics, but studies now suggest that the structure moves more like a synchronized system of catapults:

The jet propulsion of the dragonfly larvae’s mouthparts functions much more like a controllable catapult system: an internal elastic structure in the dragonfly’s head that is held by a muscle like a spring under tension. This is where the muscle’s energy is stored. The two segments of the labial mask are interconnected and are locked and triggered by a shared mechanism.

Sources & More Info:

Zoological Society of London: The Toolkit of a Hunter: Functional Morphology of Larval Mouthparts in a Dragonfly

Journal of Experimental Zoology: A Switchable Joint in the Head of Dragonfly Larvae

Discover Wildlife: How Do Dragonfly Larvae Hunt?

Science Robotics: Hunting with Catapults: the Predatory Strike of the Dragonfly Larva

Indian Institute of Technology: Prey Capturing and Feeding Apparatus of Dragonfly Nymphs

Kiel University: Bio-Inspired Robotics: Learning from Dragonflies

Orange vs. orange