Thursday, June 13, 2024

A red-banded leafhopper has red-and-blue bands across its wings and a black line across the head. (Photo: Robert Gessing)

Worldwide, there are at least 20,000 species of leafhoppers, including 2,500 species right here in North America. Leafhoppers are one of the largest families of plant-feeding insects. There are more species of leafhoppers than all species of mammals, birds, amphibians and reptiles combined. Each leafhopper species is different and sucks sap from specific grasses, shrubs or trees.

The hind legs of these insects are elongated for jumping (hence the name). They can jump great distances searching for food or to escape predators. The red-banded leafhopper (Graphocephala coccinea), also called the candy-striped leafhopper, has eye-catching red and blue horizontal bands on its wings, which it folds like a roof above its body.

A red-banded leafhopper at Fresh Pond on Aug. 21. (Photo: Joanne Mullan)

Red-banded leafhoppers feed on sap from the leaves of fruit bushes, such as raspberry and blackberry bushes. They also feed on ornamental plants such as rhododendrons and roses. Their mouthparts pierce the leaves of a host plant. Then they use their tubelike proboscis to suck out sap. After they have digested, leafhoppers expel sweet sticky droplets called honeydew that attract flies and wasps.

A pair of red-banded leafhoppers mate in Lancaster on June 21, 2022. (Photo: Tom Murray)

Adult leafhoppers emerge in spring, feed on the leaves of new plants and soon mate. The female leafhopper uses her needlelike ovipositor to poke a hole in a leaf or stem where she insert eggs in the inner tissue of a plant. In about 10 days, the eggs hatch into nymphs that feed on the underside of the plant leaves. Nymphs look like adults, except smaller and without wings. Over time, the nymphs grow and cast off their old exoskeleton. Altogether, they molt five times. After their last molt, wings appear and the insects are now adults (at only one month old!). You can spot leafhoppers until the first hard frost in the fall.

In the scientific name of the red-banded leafhopper, graph, as you probably remember from elementary school, has to do with writing; cephal means “head.” Graphocephala, therefore, refers to the black mark that looks like it was drawn with a Sharpie on the head of many species of leafhoppers. Coccinea means “scarlet,” a reference to its red stripes.

A red-banded leafhopper on Concord Avenue in Cambridge on April 22. (Photo: Kate Estrop)

Leafhoppers are quite unusual in one interesting way. They produce in their Malpighian tubules (similar to human kidneys) tiny nanoparticles called brochosomes. The particles are super water-repellent and anti-reflective, acting as a protective coating. A leafhopper excretes the nanoparticles in milky droplets, which it spreads over its legs, body and wings. Similar to waxing a car, the nanoparticles protect the insect from water and from sugary excretions from fellow sap-drinking insects. Leafhopper legs have special bristles for manipulating these hollow, soccer-ball shaped nanoparticles.

Birds, spiders and ladybugs prey upon red-banded leafhoppers. (Photo: Robert Gessing)

Leafhopper brochosomes have several functions. First, leafhopper excrete sticky sap waste. The nanoparticle coating prevents this waste from sticking to their bodies. Second, the particles protect leafhoppers from rain, dew and spiderwebs. Third, the nanoparticles scatter light, including ultraviolet light, which reduces their reflection. Therefore, they are less visible to bird and reptile predators who see visible or ultraviolet light.

The unique optical properties of brochosomes may have many useful applications in the human world, including developing drug coatings that protect against moisture, better sunscreens, coatings to harvest solar energy and thermal cloaking devices.

The red-banded leafhopper is yellow underneath. (Photo: Ramóna Molnár)

Reproducing these complex structures in the lab is not easy, but researchers at Penn State University have tried using 3D printers. Their humanmade brochosomes reduce light reflection by up to 94 percent. They’re much larger than the leafhoppers’, though: 20,000 nanometers in diameter (about one-fifth the diameter of a human hair) compare with leafhopper brochosomes that are 30 times smaller – only 600 nanometers!

There are many insects that can solve medical and engineering problems. People do not always have to reinvent the wheel; they can borrow knowledge from insects. Multiple studies have shown that insect populations are declining by 1 percent to 2 percent per year. In 20 years, one-fifth or more of all insects on the planet could be extinct – an insect apocalypse.

A red-banded leafhopper in Hopkinton on Oct. 2, 2021. (Photo: Ramóna Molnár)

Long ago (in 1987), the biologist Edward O. Wilson argued that humans cannot survive without invertebrates such as worms, insects and spiders that make up 97 percent of all animals. He wrote:

The truth is that we need invertebrates but they don’t need us. If human beings were to disappear tomorrow, the world would go on with little change. But if invertebrates were to disappear, I doubt that the human species could last more than a few months. Most of the fishes, amphibians, birds, and mammals would crash to extinction … Next would go the bulk of the flowering plants and with them … the majority of the forests and other terrestrial habitats of the world. The earth would rot. As dead vegetation piled up and dried out … other complex forms of vegetation would die off … The remaining fungi, would also perish. Within a few decades the world would return to the state of a billion years ago, composed primarily of bacteria, algae, and a few other very simple multicellular plants.

The next time you are near a berry bush or a rhododendron, look on its leaves for this remarkable quarter-inch jumping insect and ponder how such an insignificant-looking insect can contribute to complex engineering features of the modern world.

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Jeanine Farley is an educational writer who has lived in the Boston area for more than 30 years. She enjoys taking photos of our urban wild things.