Greatly elongated limbs, twig-brown coloration, and the ability to remain motionless seemingly for hours, give this rainforest mantis a look that says, “Don’t bother with a second look, I’m just a twig.”
Fallen branches and twigs pierce or rest on leaves, providing many insects with an opportunity to evolve an appearance of inedibility to most insect-hunting predators.
Last week’s adventure took us to the Amazon Basin to visit cryptic katydids bent on escaping detection by predators by mimicking plant leaves. This week we visit the Amazonian town of La Torre, Peru, then scoot a couple thousand miles north to Carara, Costa Rica, to meet a trio of fascinating insects that use a common plant part to hide from predators. Crypsis is the art of resembling a feature of the environment unattractive as a food item to a predator. Insects that have evolved colors, forms, and behaviors enabling them to blend in with their background may escape the searching eyes of hungry predators.
Several groups of insects belonging to the orders Orthoptera and Phasmatodea , grasshoppers and stick insects, have perfected the art of crypsis where twigs and branches are common features. Along a rainforest trail in La Torre, a greatly elongated praying mantis (Mantodea) perches motionless on a leaf, raptorial forelegs outstretched awaiting an unwitting fly or moth to venture too near. Like the Chinese praying mantis we met in a previous episode, a lighting fast strike with spiny forelegs will seal the fate of its prey. However, its twig-like appearance and motionless resolve likely help it escape detection by birds or monkeys looking for insects on the move.
Stick-like appendages, elongated body and head help this horse-head grasshopper hide on the branch.
Nearby on a branch of a citrus tree, a bizarre horse-head grasshopper rests motionless on a branch. These kin of grasshoppers have remarkably elongated heads with compound eyes and antennae perched at the top. A somewhat bulbous lower jaw completes a look that somehow resembles the head of a horse – well, at least to imaginative bug geeks. Unlike their carnivorous cousin the mantis, horse-head grasshoppers dine on foliage of plants.
In the rainforests of Costa Rica, a member of the walking stick clan endeavors to fool predators by looking like a stick. We met stick insects on a Maryland mountaintop habitat in a previous episode. Here in the rainforest where most insects seem bigger, large walking sticks can be found hiding amongst leaves and branches. In addition to dramatically elongated twig-like appendages and a body colored green and brown, tropical walking sticks evolved behaviors to help fool predators. When approached by bug geeks or predators, these masters of disguise sway to and fro resembling very much a small branch rocking in the breeze, a regular feature of the rainforest.
Who could resist a chance to get up close and personal with the fascinating horse-head grasshopper?
In a life and death game of hide and seek with predators, twigs and branches provide a visual refuge for many tropical members of the Orthoptera, Mantodea, and Phasmatodea clans.
Whether it’s pretending to be a branch swaying in a tropical breeze, taking a stroll across a backpack, or auditioning as a hair accessory, giant Costa Rican walking sticks always look fab.
References
The wonderful books “Insect Defenses” by David Evans and Justin Schmidt, and “Amazon Insects” by James Castner were used as resources for this episode. Bug of the Week thanks adventurous Oliver and Gracie and the crews of Posada Amazonas for providing the inspiration for this episode. We also thank the intrepid Dr. Shrewsbury for modeling the latest in insect accessories.