Caterpillars: Watsonalla binaria mimics as a dried part of the leaf

Caterpillars: the masters of mimicry

As Elias Canetti writes in his book ‘Die gerettete Zunge: Geschichte einer Jugend’, “Every class has pupils who mimic the teachers particularly well and perform for their classmates; a class without such teacher-mimics would have something lifeless about it”. In a similar way, mimicry by living organisms makes the nature lively. Usually mimicry is observed in the nature as a result of evolution in response to a selective advantage.

Q: What would you do if you want to hide yourself from a ravenous predator?

A: I would disguise myself as a twig, leaf or even poop!

Caterpillars are voracious feeders. They have soft skin so that they can withstand the developing mass that they build up between their molts. This makes them fluffy, thus easy to crawl. Softer the body, greater the threat of predators to be easily pierced. In the eyes of predators like birds, a caterpillar is a soft bodied protein bite.

As it is said that ‘good things come in small packages’, caterpillars have evolved their defenses to ward off potential predators in several smart ways. And mimicry is one of them; it is a creative twist of evolution. It is a lifesaving strategy of animals to camouflage themselves to avoid being eaten by predators.

Masters of deception

“Never attempt to win by force what can be won by deception!”

Geometrid moths (Geometridae) are remarkable for their mimicry. Nemoria outina occurs in two forms. One is the summer form; green in color that blends perfectly with the leaves of the plant. Another is the winter form; gray in color that precisely imitates the twigs of the plant. A catkin caterpillar!

Nemoria outina
Figure 1: Nemoria outina (top: summer form, bottom: winter form) (source)

Caterpillars of the genus Synchlora mostly live on the flowers and strikingly disguise themselves as flowers. What a caterpillar does is, it first chews off petal from flowers, glues them to its body with silky threads it secretes, and gets covered.

The oak hook-tip caterpillar (Watsonalla binaria, Drepaninae) is weirdly colored in green and has a bizarre cryptic shape. It feeds on the leaves of oak trees. When the leaf turns to dry, it masquerades as a dried part of the leaf. The strategy is strange but creative.

Watsonalla binaria mimics as a dried part of the leaf
Figure 2: Watsonalla binaria mimics as a dried part of the leaf

Masters of camouflage

“Instead of hiding behind the curtain, be the curtain itself; you will never be found!”

The scarce swallowtail (Iphiclides podalirius, Papilionidae) caterpillar looks like a totally normal leaf in the eyes of the avian predators. Its body is extraordinary for its beautiful pale green coloration and even has a midrib and veins on the body camouflaging like a leaf. The caterpillar almost blends perfectly with its environment.

Iphiclides podalirius mimics as a leaf
Figure 3: Iphiclides podalirius mimics as a leaf

The juvenile caterpillar of alder moth (Acronicta alni, Noctuidae) uses its body color to camouflage as bird droppings. It has white coloration at the rear end. It is so genius that it rolls its body to exhibit the white patch of uric acid that typically covers the bird poop.

Acronicta alni camouflages itself as bird poop
Figure 4: Acronicta alni camouflages itself as bird poop

Finally, would you like to find out a caterpillar in the picture below?

A geometrid moth disguising itself as a petiole of an oak leaf

Answer: A Geometrid moth disguises itself as the petiole!

Prayan Pokharel

Prayan Pokharel is a doctoral student at the Institute for Insect Biotechnology, Justus Liebig University Giessen, Germany. He experienced all these mimicries and took the pictures of the oak hook-tip, scarce swallowtail, and alder moth caterpillars when he was in field trips together with Dr. Georg Petschenka. Dr. Petschenka, an insect chemical ecologist who has handled hundreds of caterpillars, says one should often go out in the field to discover such mimicries. He believes learning directly in the field setting promotes the development of new generations of creative scientists.

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