Cicadas are among the most intriguing insects in the natural world, known for their loud, rhythmic songs that fill the air during the warm months. Because some are large, cicadas are often considered dangerous pests, but in reality, they don’t bite or sting.
Beneficial
They spend most of their lives underground as nymphs, where they aerate the soil, allowing nutrients to penetrate deeper into the Earth, thus enriching it and promoting plant growth. When they emerge, their shed exoskeletons decompose, adding organic matter to the environment. Cicadas also serve as a food source for various predators, including birds, small mammals, and other insects, contributing to the food chain.
There are over 3,000 known species of cicadas in the world, with about 190 species native to the United States alone. They vary greatly in size, color, and song but share the same fascinating characteristics that have captivated humans for millennia.
Cicadas belong to the order Hemiptera, which is commonly known as the “true bugs.” Within this order, they’re part of the superfamily Cicadoidea, which consists of two main families: Cicadidae and Tettigarctidae, a small family with only two extant species found in Australia.
Background
Cicadas date back to the Jurassic Period, over 200 million years ago, making them one of Earth’s oldest groups of insects. The largest cicada in the world is the Emperor Cicada, Megapomponia imperatoria, found in Southeast Asia, with a wingspan of up to 8 inches (20 cm). In contrast, the smallest in the world is Mogannia minuta, another Southeast Asia species. It measures only about 0.2 inches (5 mm) in length.
The largest in the U.S. is the Northern Dusk-Singing Cicada, Megatibicen auletes, with a body length of 1.5 to 2 inches (3.8–5 cm). The smallest is the Apache Cicada, Diceroprocta apache, 0.8 to 1.2 inches (20–30 mm) long. The most common species in the U.S. is the Dog-Day Cicada, Neotibicen canicularis. There are about thirty species of dog day cicadas, named for showing up during the hottest days of summer.
Davis’ Southeastern Dog Day Cicada, Tibicen davisi (Judy Gallagher / Flickr CC BY 2.0)
The two types of cicadas
There are two types of cicadas: annual and periodical. Annual cicadas usually spend two to five years underground. But they overlap, so some emerge every year. Periodical cicadas, on the other hand, have much longer developmental periods. In the U.S., those in the genus Magicicada are known for their 13- or 17-year life cycles. These nymphs remain underground for exactly thirteen or seventeen years, depending on the species, before emerging en masse to molt into adults. This synchronized emergence, which can involve millions of cicadas simultaneously, is one of nature’s most remarkable events.
External characteristics
Cicadas exhibit various color variations. The most common are shades of brown, green, black, and gray, which camouflage against the tree bark and leaves where they feed. Some species have stripes or spots, such as red, orange, or yellow, on their eyes, legs, or wing veins. The wings are usually transparent or semi-transparent and can be colored or patterned with spots or stripes.
The cicada has three main body parts: head, thorax, and abdomen, covered in a hard exoskeleton. It has large compound eyes that bulge on the sides of its head, giving it a wide field of vision. Cicadas hear through organs called tympana, which are thin, membrane-like structures on the sides of their abdomen below the wings. They function like eardrums vibrating in response to sound waves. Two pairs of wings and three pairs of legs are attached to the thorax. The veins in the transparent forewings can be easily seen. The hindwings are smaller and less visible. Cicadas aren’t the most agile flyers, but can travel short distances.
Timbal, the sound-making organ
One of the most fascinating aspects of a cicada’s anatomy is its sound-producing organ, the timbal. Located on each side of its abdomen, they’re a pair of ribbed membranes that can be rapidly buckled in and out by powerful muscles, producing a clicking sound. The rapid repetition of these clicks creates the cicada’s distinctive song, which can reach up to 120 decibels (just below a jet plane taking off). Cicada sound and video The loudest insect on Earth
Internal anatomy
A cicada’s head contains the brain and a ventral nerve cord. The brain coordinates the cicada’s behavior, while the ventral nerve cord has ganglia at each segment of the body to control local movements and reflexes.
Cicadas breathe through tracheae tubes that deliver oxygen to the body’s cells. Air enters the tracheae through small openings along the exoskeleton known as spiracles. The circulatory system is an open system where the insect’s blood, or hemolymph, circulates freely within the body cavity. Hemolymph is pumped by a dorsal vessel, which acts as a heart to distribute nutrients, hormones, and oxygen through the body. It also helps in removing bodily waste.
The mouthparts, or stylets, are adapted to pierce plant tissue and access the nutrient-rich sap. The sap travels through the esophagus to the midgut, where digestion and nutrient absorption occur. Any undigested material passes through the hindgut and is excreted as liquid waste. This efficient digestive process allows cicadas to sustain themselves on a diet that is low in solid matter but rich in sugars and other dissolved nutrients.
Reproduction
Reproduction begins with sound when males produce loud, rhythmic songs. Each species has a distinct song, which helps females identify and locate potential mates. The male’s song is not just a simple call but often includes variations in pitch, rhythm, and intensity, which may serve as a form of courtship, signaling his fitness to potential mates.
Once a female hears a call she finds appealing, she moves closer to him. The male often continues to sing as she approaches. In some species, the female may respond with clicks by flicking or snapping her wings, indicating her readiness to mate.
After mating, the female uses a sharp, blade-like structure (ovipositor) at the end of her body to cut slits into the bark or twigs of trees or shrubs. Her eggs flow through the ovipositor into the slits. They’re usually in clusters, with each cluster containing several dozen eggs. Depending on the species, a single female cicada can lay hundreds of eggs, distributing them across multiple sites to increase the chances of survival.
Pharoah Cicada, Magicicada septendecim, depositing her eggs in an apple twig (Plate 7 from “Insects, their way and means of living,” by R. E. Snodgrass, 1922 / Wiki, USDA; PD)
The eggs typically take several weeks to hatch. The tiny nymphs then drop to the ground and burrow into the soil. They’ll spend most of their lives there, feeding on plant roots and growing larger. When they’re full-size adults, they claw their way to the surface, climb onto nearby vegetation, shed their exoskeletons, and dry their wings. They’re now ready to look for mates.
Cicada adult emerging from its exoskeleton that’s still covered with dirt from being underground (© boyphare / Shutterstock)
Lifespan
The lifespan of a cicada varies by species. They spend most of their lives underground as nymphs, where they can live from two to seventeen years. For example, annual cicadas, such as dog-day cicadas, generally have a lifecycle of around two to five years, but their broods overlap, so some emerge every year. In contrast, periodical cicadas spend thirteen or seventeen years underground before emerging. As adults, annual cicadas generally live for about five weeks, and periodical cicadas for three to four weeks.
Habitat
Cicadas typically inhabit warm and temperate environments with plenty of trees and shrubs, including cities and suburbs. The 13- and 17-year periodical cicadas are primarily distributed in the eastern and central U.S. Other species, such as the dog-day cicadas, Neotibicen spp., can be found in almost every state. Overall, cicadas are found from the southern tip of Florida to the northern parts of the Midwest and across to the West Coast.
Foods
Cicada mouthparts are adapted to pierce plant tissue and feed on the nutrient-rich sap of trees and shrubs. Despite their diet, cicadas don’t cause significant harm to plants because they feed in a non-destructive manner.
Defenses and predators
Cicadas primarily rely on camouflage by blending into tree bark and leaves. Large numbers during mass emergences can also overwhelm predators—this “predator satiation” strategy ensures that even though many are eaten, enough survive to reproduce. Additionally, their sudden bursts of flight and erratic movement can make them harder to catch.
Many animals prey on cicadas, including birds, other insects, such as cicada killer wasps, reptiles, and amphibians. Small mammals, like squirrels, raccoons, and bats, feed on them, too, especially during mass emergences.
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