Membracidae, commonly known as treehoppers, are a family of insects belonging to the order Hemiptera, which also includes cicadas and leafhoppers. These small creatures, ranging from 3 to 15 millimeters in length, are distinguished by their unusual body shapes. Their unique appearance often makes them difficult to spot in their natural environments. There are over 3,200 described species of treehoppers across more than 400 genera worldwide.
The Elaborate Pronotum
A distinguishing feature of treehoppers is their enlarged pronotum, which is the dorsal plate of the first thoracic segment. This structure extends backward to cover the abdomen and, in many species, even projects forward to shield the head. The pronotum’s diverse forms serve as an effective defense mechanism, primarily for camouflage and mimicry.
These structures allow treehoppers to mimic various plant parts such as thorns, twigs, or even dead leaves. For instance, species like Umbonia crassicornis and Platycotis vittata possess sharp, thorn-like pronota, rendering them unappealing prey to animals like Anolis lizards. Some treehoppers also mimic other organisms, such as ants or wasps, further deterring predators.
The internal structure of the extended pronotum in many species is empty, highlighting its primary role as a protective and mimetic outer shell. The three-dimensional shape of the pronotum is established during earlier nymphal stages, contributing to its effectiveness.
Feeding Habits and Global Distribution
Treehoppers are herbivorous insects that feed on plant sap, specifically targeting the phloem tissue within host plants. They possess specialized piercing-sucking mouthparts, known as stylets, which they insert into plant stems to extract nutrient-rich sap. This feeding process is continuous due to the high pressure of the sap within the plant’s vascular system.
As a byproduct of their sap-rich diet, treehoppers excrete a sugary waste product called honeydew. This sweet substance is often a sought-after food source for other insects, including ants and bees. Treehoppers are found across all continents except Antarctica, with a significant diversity of species residing in tropical and subtropical regions.
They inhabit various environments, including forests, grasslands, and gardens, living primarily on the stems and leaves of a wide range of host plants. While some species are generalists and feed on multiple plant types, many are host-specific, associating with particular trees, shrubs, or herbaceous plants. This dietary specialization influences their localized distribution patterns.
Social Interactions and Parental Care
Many treehopper species engage in a mutualistic relationship with ants. Ants are attracted to the honeydew excreted by the treehoppers, which serves as a food source for the ant colonies. In exchange for this sugary reward, ants provide protection to the treehoppers, guarding them from predators and parasites.
Ants may actively tend to treehopper nymphs, sometimes even “milking” them for honeydew by gently stimulating their abdomens. This protective presence increases the survival rate of treehopper nymphs. The removal of honeydew by ants also prevents the growth of sooty mold on plants, which can hinder treehopper excretion and plant photosynthesis.
Beyond mutualism with ants, some treehopper species exhibit forms of maternal care. Female treehoppers may guard their eggs and newly hatched nymphs from predators and parasitoids. This protective behavior can involve the female sitting over her egg mass or buzzing her wings to deter intruders.
In certain species, female parental care can evolve in conjunction with ant mutualism, where mothers attract ants to protect their offspring, especially when nymphs are small and produce less honeydew. These social behaviors highlight adaptations within the Membracidae family.