Nature has no shortage of animal camouflage tricks. One newly recognized form of deception, used by plant-eating insects called leafhoppers, was thought to have a whole different purpose.
Leafhoppers are found worldwide in temperate and tropical regions. Most of the insects, of which there are about 20,000 described species, produce small quantities of microspheres called brochosomes — tiny soccer ball–like particles with honeycomb indentations. Researchers figured out that the brochosomes, which leafhoppers rub on their bodies, were used primarily to make the insects water-repellent. But why the bugs also used the balls to cover their eggs, which the insects lay on young leaves, was a mystery.
Now, using a novel method to manufacture brochosomes in large quantities, engineers found that the microparticles have the exact shape and size to prevent reflection of light in any direction. As a result, surfaces covered with brochosomes appear similar to a leaf in the spectrum of light that is visible to insects, mechanical engineer Tak-Sing Wong and his team at Penn State report online November 3 in Nature Communications. That suggests that the antireflective property of the spheres functions as camouflage for the eggs, protecting them from would-be predators such as birds or other insects.
The manufactured brochosomes have many potential applications, the researchers say, such as solar energy harvesting, where antireflective surfaces are needed.