21 Interesting Facts About Periodical Cicadas

21 Facts About Periodical Cicadas

1. Long Life Cycle: Periodical cicadas have one of the longest insect life cycles, spending 13 or 17 years underground as nymphs before emerging as adults.
2. Mass Emergence: They emerge in large synchronized groups called broods, numbering in the millions to billions, to overwhelm predators.
3. Species Variation: There are seven known species of periodical cicadas in the genus Magicicada, differentiated by their life cycles and physical characteristics.
4. Prime Number Cycles: Their 13- and 17-year cycles are prime numbers, which may help reduce hybridization and predator synchronization.
5. Brood Classification: Each emergence event is associated with a brood number, such as Brood X, which is one of the largest and most widely known.
6. Sound Production: Male cicadas produce loud, distinctive mating calls using specialized structures called tymbals.
7. Temperature Trigger: Emergence timing is linked to soil temperature, typically around 64°F (18°C) at a depth of 8 inches.
8. Feeding Behavior: Nymphs feed on xylem fluids from tree roots underground, while adults feed minimally and primarily focus on reproduction.
9. Short Adult Life: Adult periodical cicadas live for only about four to six weeks, during which time they mate and lay eggs.
10. Egg Laying: Females lay eggs in slits cut into small branches, which can cause minor damage to young trees.
11. Predator Satiation: Their mass emergence overwhelms predators, ensuring enough cicadas survive to reproduce.
12. Ecological Role: Cicada emergences aerate soil and provide a significant food source for many animals.
13. Molting Process: After emerging, nymphs climb surfaces and molt into winged adults, leaving behind exoskeletons called exuviae.
14. Geographic Range: Periodical cicadas are found primarily in the eastern United States.
15. Historical Records: Native American tribes and early European settlers documented cicada emergences centuries ago.
16. Scientific Interest: They have been subjects of study in evolutionary biology, ecology, and entomology due to their unique life cycle.
17. Climate Change Impact: Changes in climate can affect emergence timing and geographic distribution.
18. Non-Periodical Cicadas: Unlike annual cicadas, periodical cicadas synchronize their life cycle, making them unique among cicadas.
19. Human Interaction: While generally harmless, their mass emergences can be a nuisance due to noise and sheer numbers.
20. Conservation Status: Most periodical cicada species are not endangered, but habitat loss could pose risks in the future.
21. Cultural Significance: They have inspired folklore, art, and scientific curiosity, symbolizing renewal and natural cycles.

Habitat and Behavior

Periodical cicadas primarily inhabit deciduous forests and woodlands in the eastern United States. Their nymphs live underground, feeding on the sap from tree roots for 13 or 17 years depending on the species. When the soil temperature reaches a threshold, usually in late spring, the nymphs emerge simultaneously, climb nearby vegetation, and molt into winged adults. Adults are active during the day and produce loud mating calls to attract females. After mating, females lay eggs in tree branches, and adults die shortly thereafter. The eggs hatch into nymphs that fall to the ground and burrow underground to begin the cycle anew.

Why This Animal Matters

Periodical cicadas play a vital ecological role by aerating the soil during their underground development and providing a seasonal bonanza of food for numerous predators including birds, mammals, reptiles, and other insects. Their mass emergences help sustain diverse wildlife populations. Additionally, cicadas contribute to nutrient cycling when their dead bodies decompose. Culturally, they have fascinated humans for centuries, featuring in folklore and scientific studies. Understanding their life cycle and behavior can offer insights into evolutionary biology and environmental changes.

Common Misconceptions

Misconception: Periodical cicadas bite or sting humans.
Correction: Periodical cicadas do not bite or sting; they are harmless to humans and do not feed on blood.

Misconception: Periodical cicadas emerge every year.
Correction: They emerge only every 13 or 17 years, depending on the brood and species.

Misconception: Periodical cicadas damage mature trees significantly.
Correction: While egg-laying can cause minor damage to small branches, mature trees usually tolerate cicada emergences without lasting harm.

Misconception: All cicadas are periodical cicadas.
Correction: Many cicada species emerge annually; periodical cicadas are unique in their synchronized, long life cycles.