🕷️ Cicada shells: what they are and why you find them

🧾 Quick Facts

Cicada shells are the empty exoskeletons left behind by cicadas during their molting process. Known for their distinct sounds and fascinating life cycle, cicadas are captivating insects. Here are key facts about cicada shells and cicadas themselves:

• Common names: Cicada shells, exuviae
• Scientific name: Varies by species
• Insect or not: Insects; they are invertebrates with three-part bodies and six legs
• Order / family: Hemiptera / Cicadidae
• Typical size range: Adult cicadas generally measure 2-5 centimeters in body length
• Key colors/patterns: Brown, tan, and translucent when empty; living cicadas can range from green to black with colorful wings
• Activity: Typically diurnal but some species are more crepuscular
• Typical habitats: Woodlands, forests, and gardens
• Where in the world it occurs: Most continents, particularly diverse in tropics and temperate regions
• Seasonality: Most visible in late spring to late summer, depending on the region

🔍 Identification

Cicada shells are recognized by their distinct, hollow appearance left clinging to tree trunks, plants, or fences. Here are identifying features:

• Body shape and silhouette: Clinging, empty shell; the body shape mirrors that of a living nymph but with an open back where the adult emerged
• Antennae type: Short and filamentous, though usually not noticed in shells
• Wing features: Shells lack wings, but adult cicadas have large, membranous wings with visible veins
• Leg traits and movement style: Robust forelegs for digging; unable to move as a shell
• Distinguishing look-alikes: Often confused with beetle shells; beetle exuviae have fully enclosed head capsules

• Top ID Tips:
• Look for the open split along the back, indicating where the adult emerged
• Notice the clinging position, often found on vertical surfaces
• Examine the robust, digging forelegs common to nymphs
• Check for the translucent, brownish color of the shell
• Compare to beetle exuviae; cicadas have more open head area
• Recognize cicada noises during their active season for context

🧠 Basic Body Structure

As insects, cicadas have a three-part body structure consisting of a head, thorax, and abdomen. They possess six legs and an exoskeleton that they shed through molting to allow for growth. Cicada shells are the result of this natural process. Cicadas are invertebrates, meaning they lack a backbone and rely on their exoskeleton for support and protection. In adults, the large, clear wings allow for distinctive buzzing flights.

🌍 Habitat & Distribution

Cicadas thrive in various environments across the globe. While they are most commonly associated with temperate and tropical forests, they can also be found in gardens and urban areas where trees and shrubs provide suitable habitat. Cicada nymphs live underground, typically preferring sandy or loamy soils where they feed on root juices. Above ground, their emergence and molting can be influenced by microhabitats such as tree trunks and dense vegetation.

Geographically, cicadas are found on most continents, excluding Antarctica. Their presence and activity are often tied to local climate conditions. In areas experiencing habitat changes due to urban expansion or deforestation, sightings may decrease as suitable habitats become scarce.

📅 Seasonal Appearance & Activity

Cicadas are often best spotted during their respective emergence seasons. In general terms, their activity peaks during late spring to late summer, though this can vary with geography and climate:

• Most active during daytime when temperatures are warm
• Nymph emergence typically occurs after a series of warm days
• Humidity and recent rainfall can influence surface activity
• Certain cicada species may have periodical emergences every few years

🥚 Reproduction & Egg-Laying

The reproductive behavior of cicadas involves complex communication and rituals. Males are renowned for their loud and distinct calls or songs, which they use to attract females. These songs are a crucial part of their courtship process, often heard reverberating through forests.

After mating, female cicadas lay their eggs in small slits they cut into plant material, habitually on tree twigs. The number of eggs laid can vary widely, influenced by species and environmental conditions, though numbers often range in the hundreds. Eggs typically hatch several weeks later, with nymphs dropping to the ground to burrow and begin their subterranean growth phase.

🌀 Metamorphosis & Life Cycle

Cicadas undergo incomplete metamorphosis, comprising three stages: egg, nymph, and adult. Eggs hatch after being laid in plant cavities, and nymphs drop to the ground to begin an extended subterranean life, feeding on root sap. This nymph stage may last several years, with some noted periodical species remaining underground for 13 to 17 years.

Eventually, nymphs tunnel to the surface, often synchronized as a mass event, and molt into adults. Adults live a shorter life compared to their nymph phase, primarily focused on reproduction. They typically only survive for a few weeks or months above ground.

🍽️ Diet & Feeding Behavior

Both nymph and adult cicadas have piercing-sucking mouthparts adapted for extracting juices. Nymphs feed on xylem sap from plant roots while underground. Adults also feed on plant fluids, tapping directly into the stems and branches with their specialized mouthparts.

Cicadas primarily play more of a herbivorous role and are part of the greater food web as sources of nutrition for various predators.

🦉 Predators & Defense

Due to their abundance, cicadas are prey for numerous animals. Birds, mammals like bats, reptiles, amphibians, spiders, and parasitoid wasps all partake in feeding on cicadas. In response, cicadas have several defense mechanisms:

• Camouflage: Blend into tree bark and leaf backgrounds
• Startle Signs: Rapid take-off and loud flight noise
• Mass Eruptions: Overwhelming predators with high numbers during emergence
• Hard Exoskeleton: Offers some protection against bites

👥 Social Behavior & Swarms

Cicadas are primarily solitary but come together during mating seasons, often forming large aggregations. These gatherings are most noticeable during mass emergences, where synchrony offers safety in numbers and facilitates reproduction. Individual cicadas search for mates through their distinctive calls rather than complex social structures.

🧭 Senses & Communication

Cicadas have acute senses that aid in communication and survival. Their ability to produce sound is one of their most defining characteristics. Males produce loud calls using tymbals, membranes on their abdomens, to attract females.

In addition to sound, cicadas are sensitive to vibration, which plays a role in their emergence timing and predator detection. Though sight is less critical for communication, it aids in navigation once adult cicadas take flight.

🌱 Role in the Ecosystem

Cicadas serve significant ecological roles. As herbivores, they contribute to nutrient cycling by feeding on plant fluids, and their mass emergences provide food for a wide variety of predators. Dead cicadas enrich the soil, supporting decomposition and nutrient release back into the ecosystem.

Through their feeding, cicadas can influence plant structures, though they rarely cause long-term damage. Their role is primarily as prey and as participants in nutrient and energy transfer within ecosystems.

📉 Population & Conservation Notes

Cicadas remain common across their range, often abundant where habitats are suitable. However, their visibility can fluctuate with habitat changes, like urbanization, which restricts available breeding grounds. Light pollution and pesticide use are contemporary threats impacting cicada populations.

• How to Help (Low-Impact):
• Plant native trees and shrubs to provide habitats
• Reduce pesticide use in gardens and urban areas
• Allow natural leaf litter to remain for habitat structure
• Support conservation of forests and mixed woodlands

⚠️ Human Interaction & Safety

Cicadas do not bite or sting humans and are harmless in that regard. Their presence is primarily noticed through sound and sight during peak emergence periods. In the event of encountering a large number of cicadas, it is advised to appreciate their life cycle transitions but avoid unnecessary interference or destruction of their habitats.

Any reaction to cicadas or their parts is generally mild. General precautions include washing hands after contact and avoiding ingestion.

📌 Summary

• Cicada shells are the empty exoskeletons left by molting nymphs
• Habitat includes woodlands, urban gardens, and forests
• Typically most visible from late spring to late summer
• Life cycle involves incomplete metamorphosis
• Feed on plant saps with piercing mouthparts
• Predators include birds, mammals, and reptiles
• Important in nutrient cycling and as prey items
• Population common, but affected by habitat loss
• Do not bite or sting humans, pose no direct harm