Earth will feast on dead cicadas


Just as an unexpected free dinner will distract you from the leftovers sitting in your fridge, the emergence of cicadas this summer will distract predators from their usual prey. During the emergence of the 2021 Brood Escaping the birds, the caterpillars chewed up twice the number of oak leaves than usual – and the chain of effects continued. Scientists can't possibly study them all. “With this unexpected disturbance the ecosystem gets a sharp shock that changes a lot of things at once,” says Louis Yang, an ecologist and professor of entomology at UC Davis.

From birth to death, these insects shape the forest around them. As temperatures rise in late April, yellow, red-eyed cicada nymphs begin making pink-shaped holes in the ground, preparing for their grand May entrance. All of these tunnels make it easier for rainwater to move through the soil, where it can be used by plants and other dirt-dwelling microbes. Once fully grown and above ground, adult cicadas shed their exoskeleton, spread their wings, and spend their remaining four to six weeks on the ground singing (if they are male), the sexiest songs they can hear while flying. go (if they are female), and mate.

Mother cicadas use metal-enhanced saws built into their stomachs – drilling shafts of wood with elements such as aluminum, copper and iron – to cut pockets in tree branches, where they lay about 500 eggs. Sometimes, all these cuts cause the twigs to wither or break, causing the leaves to die. Although this can permanently damage a very young plant, mature trees simply discard the cut branches and continue growing. “It's like natural pruning,” says Kritsky, “which keeps hearty trees strong, protects against disease and promotes flower growth.

Once the mating season ends, so does the life of the cicada. “At the end of summer, everyone forgets about cicadas,” says Lill. “They all die. They all rot in the ground. And then they left.” By the end of June, millions of pounds of cicadas will accumulate at the base of trees, which will rot. The smell is a sensitive memory you'll never forget, says Kritsky — like stale Limburger cheese.

But these smelly corpses send huge amounts of food to the scavengers present in the soil. “The cicadas serve as a storehouse of nutrients,” Yang says. “When they come out, they release all this stored energy into the ecosystem,” giving their bodies back to the plants that raised them. In the short term, dead cicadas have a fertilizer effect, feeding microbes in the soil and helping plants grow bigger. And as their remains make their way into woodland ponds and rivers, the cicadas carry nutrients downstream, where they can fortify aquatic ecosystems far from their home tree.

They may smell like spoiled hamburger, but Yang says if you're lucky enough to host a tree full of cicadas this year, it's best to leave their bodies alone to decompose naturally. “They'll soon be gone,” he says. If the pile is particularly obtrusive, simply move them out of the way and let nature do the rest.

The thought of billions of screaming insects in your backyard may irritate your skin, but you don't need to be a passive observer when they arrive. Researchers are urging citizen scientists to send in photos of their local cicadas to help pinpoint the upcoming emergence. The Cicada Safari app developed by Kritsky acquired and verified 561,000 cicada photos during the emergence of 2021 Brood X – he expects to find even more this time.

“It's a wonderful natural phenomenon to marvel at, nothing to be afraid of,” says Lill.