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Seeking the Hidden Twiggies

Seeking the Hidden Twiggies

Of the thousands of photographs taken at the Nectandra Reserve, my most challenging ones were of two groups which I coined collectively as the “twiggies” — walking sticks (Phasmatodea) and mantids (Mantodea). The “twiggies”, while not related, share common physical traits as photo subjects.

My main frustration with photographing these insects in nature is their body shapes — long and thin, with length to width ratio reaching 15-20 at times! To fit the entire insect in the camera viewfinder means lower resolution and loss of crucial details. Without special camera gears and stacking software, well-focused photos of phasmids are few and far in-between. A good example is Fig 1, an acceptable photo for documentation but poor in details for identification.

Fig 1. Resting walking stick Diapheromera sp. (8cm, tentative identification)

My second challenge is less technical and more biological.  These insects have a maddening ability to hide in plain sight.   The order name Phasmida conjures up a ghost-like quality.  Phasma (Plato’s designation) refers to the apparition of Euridyce’s fantom (after fatal snakebite) to her husband Orpheus during his failed attempt to charm her back from the netherworld with his music.  In our real living world, these enigmatic namesakes live up to their expectations.

Most of the world’s phasmids and mantids live in the tropics and subtropics.  These herbivores (walking sticks) and insectivores (praying mantises) are usually found perched on or under plants or foliage. They are not rare. Most of them stay in place and do not fly long distances.  Yet, to see one requires a large dose of pure luck.

Imagine the challenge of spotting the delicate walking stick (inset) in the Nectandra garden (Fig 2) ,

Fig 2.

or finding this dry-leaf imitator mantis in our deeper forest (Fig 3).

Fig 3. Nectandra deeper jungle

Size Range

Phasmids range widely in body length, from a tiny 4 mm to an impressive 30 cm (0.25 – 12 in). At the small end of the scale, we encountered tiny (~8 mm) walking sticks staring back at us through the dissecting microscope when studying mosses and liverworts under magnification (Fig 4).
 

Fig 4. Walking stick moved into view under dissecting microscope at 20X magnification.

Similarly, a nearly invisible, minute praying mantis “disappeared” in the liverwort specimen under the dissecting scope until chased out of its hiding place (Fig 5, inset).

Fig 5. Praying mantis viewed in dissecting scope under 20x magnification.

At the other end of the size extreme, the stick insect depicted in Fig 6 measured 30 cm (12 in) !  It is not surprising to learn that the world’s longest insects are walking sticks. 

Fig 6. Unidentified walking stick on fern. (My middle finger measures 8cm)

How Many Ways to Hide

Phasmids are master masqueraders and concealers, day or night. To avoid detection by predators during the day, they use multiple visual trickeries.  

Immobility

The first visual deception is through motionlessness (catalepsy). 

One time on the trail, I was inspecting a tree trunk while my companion was readying his camera to photograph nearby subjects. Suddenly, I heard a sharp gasp, a simultaneous shutter click and camera flash.  This was one of those hen’s teeth moment for nature photographers — to be focusing unknowingly on a rare event while one’s camera is cocked, ready to shoot. In this case, the camera captured a “still” subject that suddenly morphed into a swaying green praying mantis (Fig 7).

Fig 7. Praying mantis on tree bark exposed through movement. Photo taken with flash.

Camouflage

The “twiggies” avoid detection, obviously, with much more than catalepsy.  Their sublime camouflage is the combination of three additional properties — crypsis, distractive body patterns as well as physical disguise.

The first, crypsis, uses coloration to blend into the background. In the following photos, note the protection of the perfectly matched color and shape of the Peruvian Shield mantis against foliage (left photo) vs. its vulnerability in an unnatural background on the right photo (Fig 8).   

Fig 8. Peruvian shield mantis Choeradodis rhombicollis

Disruptive Coloration and Form Disguise

Another astounding tool in the phasmid’s defensive arsenal is the formation of disruptive patterns and (incredible) forms on its body.  Fig 9 shows an extreme example.  Against the background of fern foliage (left), an ~8 cm bizarre form suddenly “popped” into my view. Immobile, it must have been there all along but I could not discern its form and shape until I moved . In the right photo is its stark outline against the light.

Fig 9. Phasmid Trychopeplus laciniatus perched on fern
Side view

Under different lightning, on its side, it was recognizably of phasmid shape, but with a myriad of scraggy “growths” .  When transferred to a monochromatic background the body projections were startling plantlike . Curious about the skin “growths”, I gently removed every bit of unattached debris off its torso.  Fig 10 shows its “naked” state photographed under different lighting.  The greenish moss-like projections were firmly attached, unremovable, and integral parts of its body!

Fig 10. Tricopeplus laciniatus mantid “cleaned”

The mossy projections were astoundingly life-like! Fig 11 shows insets of two different, magnified projections on the same insect.

Fig 11. Liverwort-like (upper inset) and lichen-like (lower inset) projections magnified.
Magnified view of body projections (of upper inset in left photo) viewed at different angle.

In short, just seeing and photographing these astonishing insects have been both educational and immensely entertaining to me. The ultimate reward, however, is seeing these “twiggies” in action. Remember the stick insect in my very first photo? This next one captured what happened to one of its less fortunate relatives (Fig 12). A small spider nimbly managed to grab one of the walking stick’s super long antennae and bundled it together with two spindly legs. That spelled the end of the phasmid.

Fig 12. A predator spider is lassoing one of Diapherominini two antennae, the beginning of the stick insect’s end.

Similarly, I will let my readers dub their own music to the video clip below. For all we know, Trycopeplus may be trying to imitate a wind blown leaf debris, doing its daily calisthenics or an erotic dance for its mate. But man, can it rock!

Video by Freddy Castillo