Periodical Cicadas: Nature's Timekeeping Wonders Every 13 or 17 years, parts of the Eastern and Midwestern United States witness an incredible natural spectacle. Billions of periodical cicadas simultaneously emerge from underground, their mass chorus of buzzing and clicking erupting on the landscape for the first time since the last turn of the century. This cyclical phenomenon represents nature at its most precise and intriguing. These special cicadas, known as broods, are not your average backyard insect fare. Their remarkably synchronized, decade-plus-long life cycles and massive swarms inspire awe in even the most jaded of observers. While loud and perhaps unsightly to some, periodical cicadas play a valuable role in their native habitats. Learning about their unique life histories reveals an appreciation for these insects as harbingers of seasonal change and ecological health. The Life of Periodical Cicadas Periodical cicadas begin life as rice-sized eggs deposited in the branches of deciduous trees like oaks, maples and hickories. Upon hatching, the tiny nymphs drop to the ground where they immediately start burrowing tunnels. Using their sucking mouthparts, the developing cicadas feed on sap from tree roots underground for nourishment. As the nymphs grow through five juvenile instar stages over 13 or 17 years, they track the passing seasons using biological signals and responses tuned to their specific brood’s schedule. Their internal clocks count down the years until the next mass emergence event for their brood. Different species occupy different regions based on their cycle length. When the 13th or 17th year finally arrives, the cicadas all tunnel en masse back to the surface within a few weeks of each other. Once above ground, the cicadas quickly shed their previous exoskeletons and unfurl wings, taking just hours to shift into their adult form. Now airborne, the main objective becomes reproduction. Male cicadas court females through chorus calls, vibrating loud tymbal organs to amplify their species-specific songs. Some broods even synchronize to alternate their calls between 13- and 17-year groups. After mating, females lay eggs in branches, starting the generation cycle anew. Adult cicadas perish within 2 to 6 weeks. Impacts on Ecosystems The sudden presence of billions of adult cicadas represents a major food source for all kinds of predators. Birds gorge on the protein-rich, abundant insects to fuel migration and feed chicks. Other animals like squirrels, foxes, snakes and raccoons also benefit from the movable feast. When the cicadas die off en masse, their decaying bodies return key nutrients to forest soil. Underground as nymphs, periodical cicadas play the long game in enhancing their native ecosystems. As they feed on sap, their constant burrowing and tunneling aerates soil and prunes tree roots for new growth. Mature trees weather the brief adult feeding frenzy well, only suffering light cosmetic damage. The cicadas avoid harming young trees and plants. Overall, forests renewed by cicada activity tend to show increased vigor after an emergence event. Appreciating the Cicada Symphony The most obvious sign announcing a cicada brood’s arrival is their sheer noise. Up close, the shrill chorus can exceed 100 decibels, on par with motorcycles or lawnmowers. This steady droning emanates from the cicadas rapidly vibrating tymbal organs to amplify their calls over distance in search of mates. Combined, the accumulated sounds of billions of individuals can carry for miles. While admittedly an assault on the eardrums for humans, each species contributes distinctive songs like the scattered clicks of 13-year Decim broods or the oscillating whine of 17-year Magicicada septendecim. Some broods even tune their calls to alternate back and forth. The resulting cacophony forms a kind of natural symphony, chaotic yet awe-inspiring in its synchronicity. Witnessing an emergence in person multiplies the impact. Seeing countless cicada husks left behind on trees brings home their massive numbers. Observing their bulbous black bodies and striking red eyes invites new admiration for their otherworldly appearance. And feeling the unrelenting background roar as daylight wanes recalls the pulse of nature’s endless cycles. The experience leaves a powerful impression for years afterward. A Once-in-a-Lifetime Event No two cicada emergences are exactly alike. Weather, food sources and predators influence survival rates, leading to fluctuations in brood sizes over their extended underground development. For people lucky to experience multiple emergences across different life stages, each event carries its own significance. Young children may react with delight at witnessing the novelty. Teenagers might find the insect horde gross yet fascinating. Adults likely appreciate the rarity of the cyclical occurrence. With continued climate change and habitat loss, some experts worry future cicada broods may ...
