They're out there-leafhoppers and treehoppers just waiting, their piercing and sucking mouthparts ready to drain the life out of all things green!

And what's more, these tiny insects are carrying on-sucking and chewing, leaping and crawling, singing and mating, raising their young nymphs-right in your own backyard.
Randy Hunt, assistant professor of biology at Indiana University Southeast, researches treehoppers and leafhoppers.

"Leafhoppers and treehoppers are in distinctly different families," said Hunt. "But both are plant-feeding insects that feed directly from the vascular tissue of plants."
It probably won't surprise you to learn that most treehoppers are found on trees and shrubs or that leafhoppers tend to hang out around grasses and herbaceous plants. They are the subjects of much research, because some of them are serious agricultural pests. Around 20 percent of all insect vectored plant pathogens, mostly viruses, are transmitted by leafhoppers.

Just looking at sheer numbers makes you wonder how in the world all the activity that must be taking place in your lawn and among your trees can go relatively unnoticed. According to one Web site, there are more leafhopper species worldwide than all species of birds, mammals, reptiles and amphibians combined approximately 20,000 species of leafhoppers have been described. They belong to the superfamily Membracoidea and a lineage that is at least 40 million years old. DNA and morphological evidence suggests that Membracoidea also includes the more specialized treehopper.

But enough background. According to Hunt, there is a lot of interesting stuff going on in the backyard. For example, his own work centers around treehopper and leafhopper mating behavior. Hunt's earlier work on Spissistilus festinus produced the first experimental evidence for any species of treehopper that mating behavior is mediated by vibrational communication. Last fall, NPR featured the work of a colleague Reginald Cocroft at Cornell University on treehopper and leafhopper communication, a piece which included the sounds of a marvelous insect symphony, recorded by Hunt.

Leafhoppers and treehoppers produce vibrations using a ribbed, rigid tymbal organ that pops when flexed. A number of sounds seems to be produced by abdominal vibration. The signals are complex and are transmitted through plants as minute vibrations, far beyond the range of human perception. But in comparison with birds, frogs and insects that use airborne signals, vibrational communications are relatively unexplored and poorly understood. "Perhaps our most important finding is that vibrational signals mediate competition among males for mating opportunities," said Hunt. "We've discovered that males 'chorus,' with individual males alternating singing bouts, thus avoiding song overlap. If a female were there, all males would stop exchanging calls and scramble to locate the female. Keep in mind that in this system-Graminella nigrifrons, leafhopper females mate only once, whereas males can mate many times. Therefore, virgin females are always scarce. Our work in this system shows that females mate with the first male that arrives-hence a scramble competition.
"We've also determined how chorusing behavior is regulated," he continued. "Male Graminella nigrifrons emit a call that has three sections. Our experiments suggest that the first part of the call-the snorting‹is basically a 'ready to call' phase. If another male is singing, he will shut down and then start up again in a few seconds. If the channel is clear, he will proceed to call."

But some males don't follow the rules, according to Hunt.
"Some males use an alternative mating strategy, emitting vibrational 'jamming' signals rather than search when a nearby male is 'duetting' with a female."

But in order to determine why this alternative behavior exists or what results from it, more study must be conducted as current data are inconclusive, said Hunt.

Hunt's other research interests include the role of sexual selection in driving speciation and mutualistic interactions between leafhoppers and ants. He has evidence that one species of leafhopper uses a vibrational signal to attract ants which guard leafhoppers from predators. In return, the leafhoppers provide honeydew, a sweet nutrient-rich secretion, for the ants' consumption.

"These are research questions that are not specific to leafhoppers and treehoppers, but studying these insects and their unusual mode of communication may contribute to a broader understanding of the evolution of communication systems and mating strategies," Hunt said. "But there are also potential practical benefits. Leafhoppers are important vectors of plant pathogens. A basic understanding of mating systems will provide a better understanding of plant disease dynamics. That is, being able to predict the occurrence and patterns of pathogen spread in agricultural systems."

http://www.iuinfo.indiana.edu/homepages/4-21-2000/text/treehopper.htm