Bug of the Week returns to tropical rainforests this week to meet some true masters of disguise, treehoppers. These diminutive relatives of cicadas evolved bizarre ornamentation on their bodies to help them escape rapacious predators. The first segment of the thorax of an insect is called the prothorax. In treehoppers, the dorsal plate of the prothorax is often highly ornamented with spines, globe-like structures, or elongated into the shape of a thorn. Undoubtedly, these thorny structures help treehoppers to appear more plant like than insect like, allowing them to blend in with their environment and escape the searching eyes of predators.
Not all treehoppers rely on camouflage. Many are brightly colored and highly apparent on the leaves and stems on which they feed. As is the case of the monarch butterfly and milkweed bug, dazzling coloration may warn predators of an unpleasant meal should a predator risk a taste of these colorful morsels. Like their kin, the aphids and cicadas, treehoppers are equipped with sucking mouth parts which they jab into a plant to remove nutritious liquids from vascular tissues. The products of their liquid diet are excreted in the form of honeydew, a substance highly valued by other six-legged denizens of the forest including ants.
Ants frequently attend and protect colonies of treehoppers and in return provide protection to their herd of honeydew producers, thereby ensuring a steady supply of rich carbohydrates. Treehoppers have another trick or two to reduce the toll inflicted by hungry predators. Several species have evolved parental care whereby the female treehopper remains with her young for part or all of their juvenile development. Many species of treehoppers insert their eggs directly into leaf or stem tissue.
In a tree high above the forest floor in Costa Rica, a gorgeous mother membracid stoutly defended a clutch of eggs deposited in the soft tissue of a branch. Even a gentle attack by the index finger of a bug geek did not cause this dedicated mother to abandon her brood. On a large-leafed plant in the rainforests of Belize, I discovered several female treehoppers guarding froth-covered masses of eggs deposited on the mid-vein of a leaf.
Nearby, while dozens of treehopper nymphs cavorted on the leaf blade, a diligent mother stood guard on the leaf’s petiole, the perfect spot to intercept wandering youngsters and hungry predators attempting to search the leaf for tender young treehoppers. It is fascinating to observe iconic human behaviors such as parental care in tiny creatures seemingly so different and far removed from humankind. Perhaps, they are not so far removed after all.
With mom on guard, treehopper nymphs can’t wander away and hungry predators will be contested.
The wonderful paper entitled “Sociality in Membracidae (Homoptera)” by T. Wood and “The Insects: An Outline of Entomology” by P. Gullen and P.S. Cranston were used as resources for this episode.
We thank Dr. Shrewsbury and the intrepid students of BSCI 339M ‘Tropical Biology in Belize’ for spotting treehoppers in high and low places and providing the inspiration for this episode.