by Jessee J. Smith
You may not have heard them singing, but you’ve probably heard the buzz: Brood X of the periodical cicadas (Magicicada spp.) is emerging over a large portion of the eastern U.S. this year. These big bugs belong to the order Hemiptera (true bugs) and are related to aphids and leafhoppers. Unlike those modest insects, periodical cicadas draw attention to themselves because of their unusual life cycle: after hatching from an egg about the size of a caraway seed, they fall to the ground, burrow into the soil, and spend the next thirteen or seventeen years tunneling at a leisurely pace and sucking watery xylem fluid from tree roots. After undergoing five stages of nymphal growth, they tunnel closer to the soil surface, rising and descending in response to warm spells and cold snaps as they wait for the soil temperature to reach a steady 64ºF. They may even build small mud “chimneys” at this stage, extending their burrows aboveground to avoid waterlogged soil.
Eventually, often on a warm night following a rainy day, the nymphs emerge for their final molt. They may surface by the hundreds, the grass rustling all around as they make their way to the nearest vertical surface, where they climb until they can anchor their tarsal claws and begin the laborious process of shedding their golden-brown outer skin to reveal the soft, white body beneath. The new adult exoskeleton hardens over the course of several hours, darkening to silky black while the wrinkled wings expand and orange color develops along their delicate veins.
After another day or so, the males are ready to make themselves heard. They fly to the tops of trees and form chorusing centers, where many males sing together to attract females. When the females fly in, they respond to individual males by flicking their wings when the pitch descends at the end of the male’s call. Given the signal, the male approaches the female and taps her with his foreleg. If she accepts and doesn’t fly away, they mate.
After the eggs are fertilized, the female will find a suitable egg-laying site (ideally, a hardwood twig about 3/8–1/2” diameter) and use her chisel-like ovipositor to deposit her eggs, laying them in groups of 10 to 20 until all 500 or so eggs have been safely nestled into their wooden cradle. The adults die almost immediately after mating and egg-laying, but after six to ten weeks, the tiny nymphs hatch and drop to the ground, where they will go unnoticed until they make the headlines again in 2038.
Although human reactions to this spectacle are mixed, periodical cicadas are a perfect “gateway bug” for kids (and adults) to learn about entomology. They can’t bite or sting or defend themselves with anything more than a loud squawk, and they’re easy to find and handle. In fact, cicadas are so accessible that they’re currently the subject of what may be the largest citizen science project ever focused on a single genus: Dr. Gene Kritsky and a team of researchers working with Mount St. Joseph University are mapping the emergence using the free app Cicada Safari (cicadasafari.org), which allows anyone with a smartphone to submit photos with GPS data to record cicada sightings. With over 100,000 downloads and counting, this promises to be the most thoroughly documented Brood X emergence in recorded history!
To learn more and participate in Magicicada research, visit:
Cicada Safari (https://www.cicadasafari.org): a free app that allows users to report cicada sightings by submitting photos
Brood X Cicadas: 2021 (https://www.inaturalist.org/projects/brood-x-cicadas-2021): an iNaturalist project designed to explore the distribution and abundance of the three species of Magicicada within Brood X
Cicada Mania (https://www.cicadamania.com): a fun, informative site that brings together cicada enthusiasts from all over the world
UCONN: Cicadas (https://cicadas.uconn.edu): a trove of detailed information about Magicicada, including maps of each brood and an excellent guide to the species and their calls