Cicadas (superfamily Cicadoidea) are large, distinctive insects best known for the loud, buzzing songs produced by the males during the summer months. They are often inaccurately called “locusts.” Cicadas are generally considered nuisance pests rather than destructive ones, as their feeding damage is minor. However, large emergences of **periodical cicadas** (genus *Magicicada*), which appear every 13 or 17 years, can cause significant damage to young trees and nursery stock due to the egg-laying process.
Taxonomy and Classification
Cicadas belong to the order Hemiptera (true bugs) and the suborder Auchenorrhyncha. They are classified in the superfamily Cicadoidea. Cicadas undergo incomplete metamorphosis (egg, nymph, adult). There are two main groups: **annual cicadas** (e.g., *Tibicen* species), which appear every year, and **periodical cicadas** (*Magicicada* species), which emerge synchronously every 13 or 17 years in massive numbers.
Physical Description
Adult cicadas are robust, dark-bodied insects, typically 25–50 millimeters long. They have a broad head, prominent bulging compound eyes, and two pairs of clear, membranous wings with distinct veining, often held tent-like over the body. Annual cicadas are often green and black, whereas periodical cicadas are black with striking reddish-orange eyes and wing veins.
The nymphs are subterranean, pale brown, and wingless, possessing large, shovel-like forelegs adapted for digging and tunneling through soil. Nymphs of periodical cicadas are often recognized by their dark, red eyes when they emerge. The discarded, brownish exoskeletons left clinging to trees after the final molt (ecdysis) are a common sign of emergence.
Distribution and Habitat
Cicadas are found on every continent except Antarctica. They inhabit deciduous forests, orchards, and urban landscapes where their host trees grow. The nymphs live exclusively underground, feeding on the xylem fluid from tree roots. Periodical cicadas are endemic only to eastern North America, confined to specific regions where their 13- and 17-year broods occur.
Behavior and Life Cycle
The life cycle is lengthy, lasting 2–5 years for annual species and 13 or 17 years for periodical species. The female lays eggs in slits she cuts into the tips of small, woody branches using a saw-like **ovipositor**. The nymphs hatch and drop to the ground, immediately burrowing into the soil where they spend the vast majority of their lives.
After their prolonged subterranean period, the final instar nymph emerges, climbs a vertical surface (tree trunk, wall, grass blade), molts into the adult form, and flies away. The adults live only a few weeks, focusing entirely on mating. Males produce their sound using specialized abdominal organs called **timbals** to attract females.
Feeding and Damage
Both nymphs and adults feed by inserting a piercing-sucking mouthpart into the xylem vessels of plants to withdraw fluid. This feeding is generally minor and does not significantly harm mature, healthy trees.
The main source of plant damage is from the female’s egg-laying activity (oviposition). The slits cut into small, pencil-sized branches can cause the tips of those branches to die, turn brown, and break off—a condition known as “flagging.” While this is a natural pruning process for large, healthy trees, it can **severely stunt or kill young saplings** and nursery stock, especially during a mass emergence.
Management and Prevention
Chemical control is generally ineffective against large cicada emergences, unnecessary for mature trees, and detrimental to beneficial insects. The most effective control is **cultural**. Young, high-value trees should be protected during a periodical cicada emergence by wrapping them in fine mesh netting (with a pore size less than $1/4$ inch) for the duration of the adult activity (usually 4-6 weeks).
If a major emergence is anticipated, planting new trees should be **delayed** until the emergence year is past. Pruning of damaged “flagged” branches can be done after the adult emergence period ends.
Conservation and Research
Cicadas, particularly the periodical species, are vital ecological components, serving as a massive, sudden food source for birds and mammals, effectively “satiating” predators and ensuring their own survival. Research focuses on their population cycles, the synchronicity of their emergence, and the complex mechanics of their acoustic communication.