Stop tricking me, neuropterans!

Hiking and photographing alone at night in Australia can be an unforgettable experience. On one hand, you can come face to face with animals you have never even heard about, and on the other hand you can find yourself surrounded by drunk Aussie folk who happened to pass by and got curious about what you are doing. Both possibilities are exciting and terrifying at the same time.

On one such hike, a warm and humid night in Kuranda tropical rainforest, and after pinching myself back to consciousness following an encounter where I was being drowned in beer breath, I stopped to inspect a bush that had some leaf damage. The culprit was discovered easily, but from the corner of my eye I could also see something else. A bright stain on the underside of one of the leaves, only a few millimeters in diameter, yet something about it looked a little off. A rule of thumb that I learned early on when visiting the tropics, is to be suspicious of anything that looks a bit out of place – most chances are that someone is hiding and trying to trick you. And indeed, this “stain” was a living creature. A flat disk-shaped insect larva. It was a neuropteran.

Neuropteran larva (Osmylops sp.) camouflaged on the surface of a leaf in ambush for invertebrate prey. Queensland, Australia.

I am a big fan of Neuroptera larvae. Each family is often characterized by its own unique larval form, and some of them are absolutely bizarre. When I inspected this larva closely, I realized that I have seen this body structure before. The fleshy appendages surrounding its body were a dead giveaway for family Ascalaphidae. An owlfly larva! Owlfly larvae are excellent ambush predators and usually sit patiently motionless on leaves, rocks, tree bark etc’, hoping to surprise a passing insect.

But I was wrong.
One of the things I love most about nature is that there is no shortage of opportunities to get humbled by how much you don’t know.

This is no owlfly. This larva belongs to the family Nymphidae. It’s a lacewing.
Now, this is not the first time I am fooled by lacewings. The last time was over 10 years ago in New Zealand. In this case, I can comfort myself that I was close in my guess, as the families Nymphidae and Ascalaphidae are somewhat closely related, but the truth is Nymphidae is endemic to the Australia-New Guinea region and therefore it is unique in its own right. The family also seems to have originated in the Mid-Jurassic, with many of its closest relatives now extinct and known only from fossils.

Lacewing larva (Osmylops sp.) in ambush under a leaf

Just like owlfly larvae, this Osmylops larva is an ambush predator that sits on the surface of leaves waiting for prey. Its colors complement the underside of the leaf, and staying motionless helps it to blend in and avoid detection by its prey. The feather-like appendages on each segment disrupt the body shape of the larva, allowing it to blend in better at rest, but it is also possible that they have a defensive role in detecting and deterring predators like ants. By the way, if you look carefully, some of these larvae display the common yellow-red spots to mimic leaf damage.

A different lacewing larva (Osmylops sp.) in ambush, this one has a mottled color pattern and yellow-red spots on its back to mimic leaf damage

In order to catch prey quickly, this larva has long curved mandibles that are held wide open at 180 degrees. These jaws are hidden under the feather-like appendages. When prey passes by, the jaws quickly snap shut to catch the fresh meal. As mentioned above, Osmylops larvae are very small, so I tried to figure out what kind of prey they usually catch. From my observations on what is active on the surface on leaves in the forest, it seems most likely that their prey consists of small ants, flies, or moths. Notice that the larva always sits with its head facing the leaf margin – this is not a coincidence. It is much easier and faster to catch prey that is positioned at the edge of the leaf, either by knocking it off its feet or by surprising it when it stops to “enjoy the view.”
The Osmylops larva is like a deadly peek-a-boo.

Here you can see the full glory of the Osmylops larva’s mandibles. Normally they are held hidden under the body and when triggered they snap shut on the prey, just like a bear-trap.

For those wondering, the adult Osmylops looks like a rather plain green lacewing (you can see some examples here). I would have never guessed that this elegant insect came from a round, flat, bear-trap of a larva. The transformation from larva to adult in Neuroptera is so extreme; it is among my favorite metamorphoses.

So the next time you are out in nature, don’t be shy and look closer. You might find something you did not expect, and you might learn something new! All for the better.