Quick Methods to Identify Male vs Female 17-Year Periodical Cicadas

Periodical cicadas are one of nature’s most fascinating phenomena, emerging every 13 or 17 years in massive swarms. Among these, the 17-year periodical cicadas (Magicicada spp.) are especially renowned for their synchronized life cycle and distinctive behaviors. For entomologists, nature enthusiasts, and researchers alike, distinguishing between male and female cicadas is crucial for studying their biology, mating habits, and population dynamics.

This article explores quick and effective methods to identify male versus female 17-year periodical cicadas, offering practical tips grounded in their anatomy, behavior, and sound production. Understanding these differences can enhance your appreciation of these remarkable insects during their brief but spectacular emergence.

Background: What Are 17-Year Periodical Cicadas?

Before diving into identification methods, it’s helpful to briefly understand what makes these cicadas special.

• Species: Periodical cicadas belong to the genus Magicicada. The “17-year” refers to their remarkable life cycle: nymphs live underground for 17 years before emerging simultaneously.
• Emergence: After nearly two decades underground feeding on root xylem, they emerge in huge numbers during late spring to early summer.
• Behavior: The main goal after emergence is reproduction. Males gather in choruses, singing loudly to attract females. Females respond by selecting mates and laying eggs.

This tightly synchronized life strategy helps overwhelm predators through sheer numbers, a survival tactic called predator satiation.

External Physical Differences Between Male and Female Cicadas

The most straightforward way to tell males and females apart is by observing their external physical characteristics. Here are key traits to look for:

1. Abdomen Shape and Coloration

• Males: The abdomen of male cicadas tends to be more rounded and wider at the base. It often exhibits a more vibrant orange or reddish hue on the underside.
• Females: Female abdomens are usually more tapered and slightly longer than males. The underside often shows a paler or yellowish color compared to males.

2. Presence of Ovipositor in Females

One of the most distinct female features is the ovipositor, a pointed structure used to lay eggs inside tree branches.

• Look at the tip of the abdomen: females have a dark, blade-like ovipositor protruding downward.
• Males lack this ovipositor entirely; their abdomen ends more bluntly.

The ovipositor is often visible without magnification if you carefully inspect the cicada from the side or bottom.

3. Tymbal Covers (Sound-Producing Structures)

Male cicadas produce mating calls using specialized parts called tymbals, ribbed membranes located on the sides of their first abdominal segment.

• Males have larger tymbal covers, opaque shields that protect these membranes.
• Females either lack tymbals or have very reduced tymbal covers since they do not produce mating calls.

Observing the sides of the first abdominal segment can give clues: prominent tymbal covers suggest a male cicada.

4. Size Differences

While not always consistent due to individual variation:

• Males tend to be slightly smaller or more slender than females.
• Females are generally larger due to their reproductive organs and egg capacity.

However, size alone should not be relied upon for sexing cicadas unless accompanied by other features.

Behavioral Indicators: Sound Production and Movement

Physical observation isn’t always possible or sufficient outdoors; behavior offers another way to differentiate sexes rapidly.

1. Mating Calls: Only Males Sing

One of the quickest clues in the field is listening for sound:

• Males sing loudly by vibrating their tymbals rapidly, this produces species-specific mating songs.
• Females remain silent.

If you hear a chorus of buzzing calls from a tree or bush, you’re almost certainly listening to males. When a female approaches, she may respond with subtle wing flicks but does not sing herself.

2. Movement During Courtship

Male periodical cicadas often gather in groups called choruses:

• They perch on branches or leaves while calling.
• Often move little while singing but may fly short distances between perches.

Females typically approach silently and remain still as they select mates:

• They may flutter wings gently once near a male.
• After mating, females can be observed probing twigs with their ovipositors for egg-laying.

Quick Field Identification Tips

For quick sex determination during an emergence event or casual observation, keep these practical tips in mind:

1. Listen First: If it’s singing loudly nearby, you’re hearing males.
2. Visual Check for Ovipositor: Quickly glance at the rear end, pointed ovipositor means female.
3. Look at Abdomen Shape: Rounded and broader suggests male; tapered and elongated usually female.
4. Check Tymbal Covers: Prominent covers on side of abdomen indicate male.
5. Observe Behavior: Group singing = males; silent approaching = likely female.

Combining these cues will increase your accuracy in identifying sexes rapidly without needing special equipment.

Using Magnification Tools for More Accurate Identification

When possible, using a hand lens (10x magnification) or portable microscope enhances identification accuracy:

• Enhance visibility of tymbal membranes and covers.
• Clearly see ovipositor shape and size.
• Examine markings on ventral abdomen for sex-specific coloration patterns.

Many entomologists carry such lenses during fieldwork as part of their insect collecting kits.

Why Sex Identification Matters in Cicada Studies

Understanding which individuals are male or female is not merely an academic exercise, it has practical implications:

• Population assessments: Knowing sex ratios helps assess reproductive viability.
• Behavioral studies: Observing calling patterns requires identifying singers (males).
• Conservation efforts: Some regional broods face habitat threats; knowing sex distribution informs protection strategies.
• Public education: Accurate information enhances citizen science projects tracking emergences.

Common Misconceptions About Cicada Sexing

When learning how to differentiate males vs females, beware some common pitfalls:

• “All large cicadas are female”: Size varies widely; always confirm with other traits.
• “Only males fly”: Both sexes can fly well; flying behavior alone isn’t reliable.
• “Females produce sounds”: Females are silent; any singing cicada is male.

Always use multiple identification cues rather than relying on a single characteristic.

Summary: Fast Identification Checklist

Final Thoughts

The emergence of 17-year periodical cicadas is an awe-inspiring event that captivates people worldwide. Knowing how to quickly distinguish male from female cicadas adds depth to this experience, whether you’re a casual observer, educator, or researcher. By combining observations of physical traits like the ovipositor and tymbal covers with behavioral clues such as sound production, anyone can become adept at identifying these fascinating insects’ sexes with confidence.

Next time you encounter one of these spectacular insects during an emergence, try applying these quick methods, you’ll gain new insights into their compelling life story hidden beneath those buzzing choruses!

References & Further Reading

• Alexander RD & Moore TE (1962). “The Evolutionary Relationships of 17-year Periodical Cicadas.” Evolution.
• Williams KS & Simon C (1995). “The Ecology, Behavior, and Evolution of Periodical Cicadas.” Annual Review of Entomology.
• United States Forest Service: Periodical Cicadas Fact Sheet
• Magicicada.org – A website dedicated to periodical cicada research and education