We hear them all summer long, but how much do you really know about cicadas? Cicadas are insects, best identified by the songs made by male cicadas in the heat of summer. There are over 3,000 different species of cicadas, covering much of the globe - from Canada to Europe to Australia.
Male cicadas produce their distinct song by flexing their tymbals, which are organs found in their abdomen. By flexing small muscles surrounding these organs, a noise is produced which is amplified by their hollow abdomens. Each species creates their own unique noise which can be heard and identified by females of the same species up to a mile away! Some species can create a noise that reaches greater than 100 decibels, which is the noise of a motorcycle starting up! While this noise is mainly used as a mating call, it is also used to deter predators such as birds.
The common life cycle for cicadas begins with small eggs being laid by females into grooves they dig into trees. Females can lay up to 400 eggs and will distribute them among several sites. After the eggs hatch, the juvenile cicada feeds on the tree fluids until it falls to the ground and burrows deep into the earth. Cicadas burrow deep into the ground until they find roots to feed on. A common misconception is that cicadas remain dormant below ground, hibernating, but this is not true. Cicadas remain very active below ground, feeding and tunneling, and can remain underground for 2-17 years. During their time below ground, cicadas help improve soil structure and health. Due to their tunneling, cicadas help aerate the soil which helps water and nutrients to be dispersed in the soil and reach plant roots.
After 2-17 years, the cicadas emerge from the ground as nymphs. The nymphs climb the nearest tree and shed their exoskeleton. Once the exoskeleton is shed, their wings fill with fluid and their body hardens. The cicadas are then ready to start their brief adult life, find a mate and reproduce. Once the cicada dies, their bodies fall back down to the ground, decompose and return valuable nitrogen back into the soil - completing the circle of life!
Some species of cicadas follow a different life-cycle than the one explained above. Some species have annual life-cycles, where they burrow and emerge each year. Another type of life-cycle for cicadas are proto-periodical. Species that follow this life-cycle can emerge every year, but some years they emerge in very large numbers. This type of life-cycle is most common for species living in North America. Periodical cicadas do not cause destruction - as is common with locusts- but up to 1.5 million cicadas can occur in one acre at a time (SOURCE). Cicadas do not eat vegetation, but rather suck the sap out of the tree branches and roots through the plant’s xylem (the vascular tissue that carries water and nutrients throughout plants).
Due to their strange and amazing life-cycle, several cultures regard cicadas as powerful symbols of rebirth. In ancient China, cicadas were considered ‘high-class’ symbols of purity which rulers should follow and were adapted as motifs in imperial courts wardrobes. Cicadas are an important source of protein for many cultures, even being viewed as a delicacy by some. Even if you don’t view them as such, they are incredible creatures that have an important role in the health of our ecosystems!