The cicada, often heralded by its distinctive and resonant song, is an intriguing insect that has captivated human interest for centuries. Known for their cyclical life patterns and impressive vocal abilities, cicadas are more than just noisy summer residents.
In this article, we delve into the world of cicadas, exploring their biology, behavior, and the unique role they play in our ecosystems.
The Cicada at a Glance
|Genus:||About 200 genera|
|Species:||More than 3,000 species|
|Average Size:||2 to 5 cm (0.8 to 2 inches)|
|Average Weight:||Varies, typically light due to exoskeletal body|
|Average Lifespan:||2 to 17 years (depending on species)|
|Geographical Range:||Worldwide, except in extreme polar regions|
|Conservation Status:||Most species are not endangered, but some specific local populations are threatened or declining|
Species and Subspecies
Cicadas are categorized into roughly 3,000 species, broadly divided into two primary groups: the annual cicadas and periodical cicadas. The former appear every year, while the latter are known for their unique synchronized emergence every 13 or 17 years, primarily in North America.
Annual cicadas are larger, green or brown, and more common worldwide. Periodical cicadas are smaller, black, red, and white, known for synchronized, mass emergences.
Notable genera of cicadas:
- Magicicada: A genus of periodical cicadas in North America, known for their 17-year cycle.
- Platypedia: Common in western North America, known for their less synchronized life cycles.
- Cicadetta: Found across Europe, these are known for their diverse songs and varied habitats.
Each species has distinct calls, sizes, and life cycles, adapting to a wide range of ecological niches globally.
Cicadas are known for their prominent set of wings and large, bulbous eyes set on either side of their well-defined head. Their physical characteristics include:
- Body Size: Typically ranging from 2 to 5 cm (0.8 to 2 inches).
- Color: Varies widely among species, from green and brown in annual cicadas to black, red, and white in periodical cicadas.
- Distinctive Features: They possess a robust body, transparent wings held roof-like over the body, and membranous front wings.
- Anatomical Features: Cicadas have three small ocelli (simple eyes) located on the top of the head, which are thought to be used to detect light and dark. They also have tymbals, which are specialized organs used to produce their distinctive sounds.
Sexual dimorphism is minimal in cicadas, although males are typically more vocal and have structures known as tymbals for producing sound, which females lack.
Habitat and Distribution
Cicadas are found worldwide, they are present on every continent except Antarctica, with a high diversity in tropical regions. Cicadas are typically found in temperate to tropical climates, inhabiting forests, grasslands, and urban areas. They thrive in areas with plenty of trees or shrubs, as they feed on sap and lay their eggs in branches.
Cicadas are intriguing for their behavioral patterns, particularly their life cycles and sound production. Most cicadas are diurnal, becoming active during the day to feed and mate. Periodical cicadas are known for their mass emergences every 13 or 17 years.
Cicadas are mostly solitary insects, but periodical species emerge in huge numbers, creating large, noisy aggregations. Males produce loud, distinctive songs using tymbals to attract females. Each species has a unique song. These sounds can be heard up to 1 mile away in some species.
Cicadas spend most of their life underground as nymphs, feeding on root sap. Their synchronized emergence is a survival strategy known as predator satiation, where their sheer numbers overwhelm predators.
These insects play a significant role in the ecosystem, serving as a food source for various predators and aiding in nutrient cycling when they die. Their periodic emergence also provides a unique opportunity for scientific study and understanding of ecological dynamics.
Diet and Feeding Behavior
Cicadas have a specialized diet and unique feeding behavior. They are exclusively herbivores. They feed on the sap of a variety of trees and plants. The sap provides all the necessary nutrients for their development.
Cicadas use their piercing mouthparts, known as a rostrum or beak, to tap into the xylem or phloem of plants and extract the sap. The nymphs, living underground, feed on root sap, while adults feed on above-ground parts of plants.
Despite their large emergences, cicadas face numerous natural predators. Cicadas are preyed upon by a variety of animals, including birds, bats, spiders, wasps, ants, and small mammals. Even fish are known to eat cicadas when they fall into water bodies.
The mass emergence of periodical cicadas every 13 or 17 years serves as a feast for many predators. Their strategy is to emerge in such vast numbers that they saturate their predators, ensuring the survival of the species despite heavy predation.
Reproduction and Life Cycle
The life cycle of cicadas, particularly of periodical species, is one of the most fascinating aspects of their biology:
After emerging and undergoing their final molt, adult cicadas spend their brief adult life mating and laying eggs. Males attract females with their loud calls, and mating occurs soon after.
A female cicada can lay up to several hundred eggs. These eggs are deposited in slits made in tree branches. After hatching, the nymphs fall to the ground and burrow underground, where they will live for several years before emerging to repeat the cycle.
The nymph stage can last anywhere from 2 to 17 years, depending on the species. This long developmental period, followed by a brief but active adult stage, is a unique aspect of their biology and a subject of ongoing scientific research.
Conservation and Threats
Cicadas are generally not considered endangered or threatened:
Most cicada species are abundant, especially the periodical cicadas known for their massive emergences. However, specific local populations can be impacted by habitat destruction and environmental changes.
Habitat loss due to urbanization and deforestation is a primary threat to cicada populations. Pesticides and pollutants can also affect their survival.
Conservation efforts for cicadas are not as prominent as for other species, largely due to their widespread abundance. However, studying their patterns can provide insights into ecosystem health and biodiversity.
- Cicadas are among the loudest insects in the world, with some species capable of producing sounds louder than 100 decibels.
- The 17-year periodical cicada is the longest-living insect in North America.
- Cicadas have been a part of human culture and cuisine in various parts of the world.
- The mass emergence of cicadas is a phenomenon that still puzzles and fascinates scientists.
- Some cicada species have a symbiotic relationship with certain fungi, which can impact their development and lifecycle.
Frequently Asked Questions
How long do cicadas live?
Most cicadas live as nymphs underground for 2-17 years, depending on the species, with a brief adult life of several weeks to a few months.
What do cicadas eat?
Cicadas feed on plant sap, both as nymphs (root sap) and adults (tree sap).
Why do cicadas make so much noise?
Male cicadas produce loud calls to attract females for mating. Each species has a unique call.
Can cicadas harm humans or pets?
Cicadas are harmless to humans and pets. They don’t bite or sting.
Why do some cicadas only emerge every 17 years?
The 17-year cycle is a survival strategy to avoid predators through predator satiation and by emerging in years that don’t align with predator population peaks.