Cicadas

Brood X is on the brink of clawing their way out the soil after nibbling roots for nearly 20 years. Brood X refers to this year’s cicada event.

Newly emerged cicada (Ollllonate) CC BY-SA 4.0

I lived in Virginia during an emergence year. It was an experience I’d rather not repeat. While not as bad as the Midwest’s plague of locusts, there were cicadas everywhere. They coated windshields, driveways, and roads. They flew into you, clinging to your clothes and hair. The noise was enough to drive any sane person crazy. And then it was over. Like it never happened, except that there were hollowed out exoskeletons attached to every tree you saw. But finally, it was quiet.

Swarm of live and dead cicadas at the base of a tree (knorby) CC BY-ND 2.0

As you may know, I use sticky barriers around the trunks of my fruit and nut trees to thwart crawling insect pests. These barriers also give me a chance to see which insects are out and about, though the sticky sheets hanging in the trees do a much better job of that. This year, I was very surprised to find cicada exoskeletons caught in the barriers protecting my navel citrus tree. I thought cicadas were only on the East Coast, but I was mistaken.

Cicada exoskeleton caught by sticky barrier (Kate Russell)

Cicadas are well known on the East Coast for their epic numbers, mind-numbing noise, and littering trees and shrubs with exoskeletons. What I didn’t know is that the West Coast has cicadas, too. And this is the year, coast to coast, when billions of cicadas come out of the ground to mate. Most of them have been underground for 17 years.


Types of cicadas

Cousin to leafhoppers, there are more than 3,000 types of cicadas around the world and more than 170 species in North American that we know of. There are two cicada families: one lives in Australia and the other lives everywhere else except Antarctica. Within that global family there are annual cicadas and periodic cicadas.


Periodic cicadas (Magicicada) are native to North America and they spend most of their lives underground as nymphs. Here, they feed on sap from tree roots. Depending on the species and location, these nymphs emerge at 13- or 17-year cycles in those mind-boggling numbers. Periodical cicadas include M. septendecim, M. cassini and M. septendecula. These synchronized mass emergences make predators less likely to rely exclusively on cicadas as food and the massive numbers ensure the survival of the species.


Most annual cicadas emerge every year, though they can spend up to 9 years underground. Unlike periodic cicadas, the emergence of annual cicadas is not synchronized. Annual cicadas are also known as jarfly or dog-day cicadas because they tend to emerge in mid-summer. In my California landscape, I probably have annual citrus cicadas (Diceroprocta apache), though there are several other cicada species present.

Annual citrus cicada (xpda) CC BY-SA 4.0

Cicada description and lifecycle

Cicadas are true bugs with large, wide set eyes, clear forewings, and short antennae. They are stocky, substantial bugs that are generally active during the day. While the Malaysian emperor cicada is nearly 3 inches long with a wingspan of up to 8 inches, most cicadas are significantly smaller than that and thank goodness! Most adult cicadas, or imagos, are 1 to 2 inches long with comparably smaller wingspans.


After mating, female cicadas cut slits in the bark of twigs where they lay their eggs. When the eggs hatch, the nymphs are pale and about the size of a grain of rice. They drop to the ground and use their strong front legs to burrow as much as 8 feet into the soil. Here, they will feed on xylem sap from the roots of trees and shrubs. They prefer ash, cypress, maple, oak, and willow, but will feed on other trees, as well. In the final instar, they return to the surface where they shed their skins and emerge as flying adults. Those shed skins are commonly found attached to trees.

A cicada drying itself after molting (Martin Nielsen) CC BY-SA 4.0

​Cicada sounds

If you’ve ever been present for a cicada emergence, you know how incredibly noisy these insects can be. At up to 120 dB, they are the noisiest insects on Earth. They are so loud that they can cause permanent hearing loss when experienced at close range.


Both males and females have membranous structures called tympana that detect sounds. When a male cicada sings, he turns his tympana off so as not to damage his own hearing. [I used to have a neighbor like that. I had to move to a new apartment.]


Male cicadas create all that noise using organs called tymbals found on their abdomen. In some species, both males and females rub their wings over a series of ridges found on the thorax. These bugs have resonating cavities and membranes that amplify the sound. While we can’t tell the difference, it ends up that each male cicada has a unique song composed of modulated clicks that sound, to us, like continuous notes. I have to assume that the female cicadas can tell the difference. To me, they’re just very noisy. I did learn that one of the Australian cicada species does not produce audible sound. Instead, they produce vibrations that are transmitted through whatever tree they are on, which sounds far more civilized to me. And some cicada songs are so high-pitched that we can’ hear them. Another interesting notes about cicada courtship is that different cicada species may be found on the same tree, but that each species uses a different height from which to operate.


Adult cicadas feed on sap from xylem tissue, but they generally do not harm mature trees and shrubs. Newly planted trees and shrubs should be protected with netting during emergence years. In most cases, cicada root feeding is not significantly destructive. Females have been known to lay eggs on asparagus, citrus trees, date palms, and grapevines.


This year’s cicadas are being called Brood X. As temperatures rise, they stop nibbling the roots of your plants and emerge from the soil to mate, lay eggs, and die. Ants, bats, birds, squirrels, spiders, and wasps will all gorge on cicadas this year. While cicadas do not bite or sting, they are also not very bright and may mistake you for a tree and try to feed.


​Don’t bother spraying pesticides or insecticides for cicadas. The damage they do is minimal and you would have to use gallons of the toxic stuff to counteract a periodic emergence. If you simply cannot tolerate the noise, use it as an excuse to spend a week in Hawaii.


Cicadas are eaten in many parts of the world. In China, nymphs are deep-fried. Supposedly, they are pretty tasty when dipped in chocolate. I don’t think I’m ready for that just yet. The French onion crickets were about as far as I feel comfortable.