Why do cicadas make noise

Overview

Cicadas are insects belonging to the family Cicadidae, with over 3,000 described species worldwide, though many more likely remain undocumented. These insects have existed since the Triassic period approximately 200 million years ago, making them among the oldest living insect groups. Cicadas are best known for their loud mating calls, which vary significantly between species and can serve as acoustic signatures for identification. The insects undergo incomplete metamorphosis, progressing from egg to nymph to adult without a pupal stage. Nymphs live underground for most of their lives, feeding on xylem fluid from tree roots, with development periods ranging from 2-5 years for annual species to 13 or 17 years for periodical species. The synchronized emergence of periodical cicadas represents one of nature's most remarkable biological phenomena, with entire populations surfacing simultaneously after spending over a decade underground.

How It Works

Cicadas produce sound through specialized structures called tymbals, which are paired ribbed membranes located on the first abdominal segment of males. When muscles contract, they cause the tymbals to buckle inward rapidly, producing a clicking sound. As the muscles relax, the tymbals snap back to their original position, creating another click. This rapid buckling and snapping—occurring at frequencies between 120-600 times per second—generates the characteristic buzzing or droning sounds. The hollow abdomen amplifies these vibrations, functioning as a natural resonance chamber. Different species produce distinct calls by varying the frequency and pattern of tymbal vibrations, with some tropical species creating continuous choruses exceeding 120 decibels. Females respond to these calls by flicking their wings, producing a quieter clicking sound that guides males toward them. Environmental factors like temperature affect sound production, with cicadas typically calling most actively during the warmest parts of the day.

Why It Matters

Cicada choruses play crucial ecological roles, serving as acoustic signals that synchronize mating across populations while overwhelming predators through sheer numbers—a survival strategy called predator satiation. Their emergence provides substantial nutritional resources, with decomposing cicada bodies enriching soil nitrogen levels by up to 200% in affected areas. These insects serve as important food sources for numerous predators including birds, mammals, and reptiles, with studies showing some bird species increase reproductive success during cicada emergence years. Cicada nymphs aerate soil through their tunneling activities, improving water infiltration and root growth. Their synchronized life cycles have inspired mathematical models in population biology and provided insights into evolutionary adaptations to predation pressure. Additionally, cicada wing nanostructures have inspired biomedical research into antibacterial surfaces due to their natural nanopillar structures that mechanically rupture bacterial cells.