Periodical cicadas

Periodical Cicadas (Magicicada) are a genus of cicadas in the family Cicadidae, known for the unique phenomenon of synchronized emergence from the ground in large numbers at extended intervals of either 13 or 17 years, making them an interesting subject of study in the fields of entomology and ecology. These insects are native to eastern North America and are celebrated for their remarkable life cycle, which involves long periods of underground development followed by a brief but intense period of adult activity.

Life Cycle

The life cycle of periodical cicadas is divided into five stages: egg, first through fifth instar nymphs, and the adult stage. After mating, female cicadas lay their eggs in the slits they cut in the twigs of trees. Upon hatching, the nymphs drop to the ground and burrow underground to feed on the sap from tree roots. This underground phase lasts either 13 or 17 years, depending on the brood. During their final year underground, the nymphs construct an exit tunnel to the surface and emerge synchronously in massive numbers, usually in late spring to early summer. This phenomenon is believed to overwhelm predators through sheer numbers, allowing enough cicadas to survive and reproduce.

Broods

Periodical cicadas are categorized into broods based on the year they emerge. There are 15 identified broods: XII (12) broods of 17-year cicadas and III (3) broods of 13-year cicadas. Each brood is identified by a Roman numeral. The emergence of these broods is highly synchronized within the same geographical area, but different broods emerge in different years and locations across the eastern United States.

Morphology

Adult periodical cicadas are characterized by their black bodies, red eyes, and clear wings with orange veins. They are approximately 2.5 cm (1 inch) in length. The most distinguishing feature between the 13-year and 17-year cicadas, apart from their life cycle length, is subtle differences in size, coloration, and the pitch of their mating calls.

Behavior and Ecology

The primary activity of adult periodical cicadas is reproduction. Males produce loud, distinctive mating calls to attract females. After mating, females lay eggs, and the cycle begins anew. The mass emergence of cicadas significantly impacts local ecosystems. The abundance of cicadas provides a food source for a variety of predators, and the death of the adult cicadas after mating delivers a substantial influx of nutrients to the soil.

Conservation

While periodical cicadas are not currently considered endangered, their unique life cycle makes them vulnerable to habitat destruction and climate change. Urbanization and deforestation can disrupt the underground phase of their life cycle, and unusual weather patterns associated with climate change may affect their synchronized emergence.

Cultural Significance

Periodical cicadas have been a subject of fascination and cultural significance in the regions where they emerge. Their predictable, yet infrequent appearances have been documented and celebrated in various ways throughout history.

See Also

• Cicada
• Entomology
• Ecology of North America

External Links

• Cicada Mania - A website dedicated to cicadas, including periodical cicadas.
• Magicicada.org - A website providing detailed information on the periodical cicadas.