As I wandered through the long grasses surrounding Dead Man's Bog, I noticed small green flecks popping up above the grass in somewhat sporadic movements, seeking to avoid my thundering footfalls. You may notice these yourself on a warm day, these small insects hopping just a step ahead, as if leading you onward through the grass.
Image Source: Bruce Marlin, 2009 via Wikipedia
These tiny trail guides are called treehoppers. While the treehoppers collected from the bog fall into a grass-residing species (Three-pointed Alfalfa Hopper), this group of insects spend most of their time among the shrubs and trees on which they feed, as the name implies.
Image: Three-pointed Alfalfa Treehopper
Image Source: Kyle Kittelberger, 2013
The name "treehoppers" refers to the Superfamily Membracoidea under the Order Hempitera, containing the families Aetalionidae, Melizoderidae, and Membracidae (Deitz et al., 2008). These are not to be confused with leaf- or planthoppers which fall under the same order, but different families with different anatomical distinctions.
As is a hallmark of Hemiptera, treehoppers do not undergo complete metamorphosis, but have a smaller and less developed version of the adult with similar anatomy. The image below shows the development of the treehopper from egg to nymphal to adult stage.
Image: Life stages of the treehopper. For a zoomed in version, go here. Image source: National Library of Medicine, 2010
Treehoppers are distributed throughout the world, but are more numerous in neotropical regions (Deitz et al., 2008). In tropical regions, treehoppers engage in polyphagy, whereas those in the Neartic regions feed on singular plant species or families (Deitz et al., 2008). Due to the biodiversity of plants and trees in this region, there is a range of treehopper visual characteristics, most notably in the expression of the pronotum. Unlike most insects, the pronotum extends from above the head and back over the abdomen. The pronotum helps to provide camouflage for the treehopper, sneakily disguising it as a leaf, thorn, or twig on the tree (Missouri Department of Conservation, n.d.). The treehopper is distinguished and identified not only by this pronotum, but also by rows of 3 large setae on the back tibia (Deitz et al., 2008).
Image: Variations of treehopper pronotum adaptations
Image Source: Nature, 2011
Like the rest of Order Hemiptera, treehoppers have beak-like mouthparts which they use to feed on the phloem of trees and other plants. The saliva of the treehopper keeps the hole in the tree from closing up so that the treehopper can sit and eat for days at a time if it is secure (Barrat, 2017). In this way, treehoppers have the potential to introduce pathogens and mold into plants which can turn out to be an issue having agricultural and economic implications (Barrat, 2017). Because of this, treehopper species are monitored if they are found on crops by the USDA as they come into the States (Barrat, 2017).
Treehoppers also create "honeydew", a sugary substance that is the byproduct of liquid-feeding arthropods. Like ant-aphid relationships, treehoppers often have symbiotic relationships with ants in which they receive protection from predators, while ants receive the honeydew for food (Deitz et al., 2008).
Unlike many other insects we have learned about, some species of treehoppers provide protection to their eggs after they are laid. After ovipositing on the surface of a leaf or directly into twigs, adult treehoppers will guard their young and eventually help the nymphs to find access to the phloem of the plant by boring a whole into the twig (Deitz et al., 2008). The adult will then stay nearby, communicating with its young through species-specific vibrations that can be felt through the plant up to 1 meter away from the insect (Barrat, 2017). The vibrations are not only communication between adults and young, but also between other adult individuals.
Next time you are looking at a tree, look twice! You may just find yourself a treehopper.
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