Before we delve into the specifics about the cicada life cycle, let’s start with the thing that cicada are most known for, which is their mating call. The Green Grocer Cicada from Australia was once crowned the loudest bug in the world as its song reaches decibel levels as high as 90 (that’s equivalent to a train whistle at 500 feet away). It is also in the range where sustained exposure may result in hearing loss.
However, the recently discovered water boatman species Micronecta scholtzi (the bug with the “singing penis”) was measured at 105 decibels. Fortunately this creature lives underwater so humans aren’t exposed to its intense sound. Still, the cicada’s song is the loudest insect sound heard on land.
Because there are over 2,500 species of cicada, there are at least that many different songs. What’s more interesting is the common cicada song is performed at different tempos depending on the temperature outside. The higher the temperature is, the faster the tempo of the song.
One of the loudest songs is that of the 17 year cicada. These songs are produced by the male insects vibrating membranes on their abdomens, which are called tymbals. Females don’t have tymbals. These tymbals are contracted and released in a rhythmic pattern to produce the clicking sounds of the song.
The extreme volume is produced by the insect by using its entire abdominal cavity as a resonating board. Variance in volume is achieved by the cicada angling its abdomen toward and away from the ground. In addition to the mating call, some cicada have a quieter courtship song that is used once a female has responded to the mating call.
If a cicada is grabbed by a predator or feels threatened, it may produce a loud, asymmetrical sound. This is meant to be both a warning to other cicada and a defense mechanism to shock the predator into dropping its violently loud prey.
A cicada begins its life as an egg that has been deposited in the bark of a small twig. Here the eggs are protected from predators until they hatch.
Once a cicada hatches, it immediately drops to the ground and begins to burrow into the soil. These nymphs will burrow down one foot to nine feet into the soil and begin feeding on plant roots. Their specially equipped proboscis can pierce thick roots to suck out the juices from the plants. They also have strong front legs to help them dig through even thick clay soils.
Depending on the genus of cicada, this stage can last anywhere from 2 to 17 years. During this time, the nymph will go through several instar stages. When it reaches the final instar stage, the cicada burrows up to the surface and emerges. It immediately attaches itself to a tree or large plant and molts its skin. The adult cicada breaks out of its skin, leaving it still attached to the bark, and spends the final few weeks of its life searching for a mate.
The males begin to sing almost immediately after molting. Once the males and females have produced fertile eggs (there may be several batches) they die. See the image on the left for cicada drawings. Lifecycle images are presented from the earliest nymph stage to full adult.
So, what does a cicada look like? Cicadas vary in size from one inch to upwards of six inches. They have cylindrical bodies with the females being larger around than the males with large heads and two extremely large eyes. These two large eyes are offset with three smaller eyes located between them on the forehead. Their large wings cover a full two-thirds of their bodies and are often seen creating a protective dome that extends well past the end of the body.
Coloration is not consistent between species; they can be found in colors ranging from black to bright green with several varieties in the brown range. The eyes can be any color from red to brown, yellow, orange, white or blue.
The best way to think of it is like this. A cicada looks like a fly that has ingested a magical growth formula or as my kids like to say, “It’s a fly on steroids!”
Predators and Prey
Contrary to common belief, adult cicada do not spend their entire above ground life not eating. When they emerge, they are sometimes confused with locusts, but they don’t graze on crops. They still use their proboscis to feed on the xylem of soft stemmed plants.
On the flip side, cicada are prey for many birds, a particular strain of wasp, fish and humans. Cicada live in almost all temperate and tropical habitats and thus have a variety of predators from the wild American Turkey to the Australian bass. To deal with this danger, the cicada have developed an odd defense mechanism called predator satiation. They emerge in such large numbers that the predators eat until they are satisfied and the remaining cicada are left to mate in peace.
- Image: Molting Cicada by Brian1442 under public domain
- “Cicadas of Michigan.” University of Michigan Museum of Zoology. Web. 26 Aug. 2011. http://insects.ummz.lsa.umich.edu/fauna/Michigan_Cicadas/Michigan/Index.html
- “Cicadas, Cicada Pictures, Cicada Facts - National Geographic.” Animals - Animal Pictures - Wild Animal Facts - Nat Geo Wild - National Geographic. Web. 26 Aug. 2011. http://animals.nationalgeographic.com/animals/bugs/cicada/
- Image: Cicada Life Cycle by Pengo under public domain