Friday, March 12, 2021

Flight of the cicada: Insect gears up for big event

cicada maniaMeet the Cicada Beetle.  They are big, noisy and make an appearance by the billions every 13-17 years.

May 2021 marks the month and year that we here in New York will experience a natural phenomenon of the insect world.  This phenomenon about to happen is named Brood X or The Great Eastern Brood.  Starting in May of this year, for five to six weeks, it will be virtually impossible to miss Brood X, which will be the most widespread and prolific of the known generations of cicada in the U.S.

Cicadas are members of the superfamily Cicadidae and are physically distinguished by their stout bodies, broad heads, clear-membraned wings, and large compound eyes.

There are more than 3,000 species of cicadas, which fall into roughly two categories: annual cicadas, which are spotted every year, and periodical cicadas, which spend most of their lives underground and only emerge once every decade or two.  While annual cicadas can be found throughout the world, periodicals are unique to North America. Periodical broods are concentrated in the central and eastern regions of the United States, and some areas are home to multiple broods.

Life cycle

The cicada life cycle has three stages: eggs, nymphs, and adults. Female cicadas can lay up to 400 eggs divided among dozens of sites—generally in twigs and branches. After six to 10 weeks, young cicada nymphs hatch from their eggs and dig themselves into the ground to suck the liquids of plant roots. They spend their entire developmental period in these underground burrows before molting their shells and becoming an adult.

The developmental process varies in length, but periodical broods emerge in synchrony depending on the year and soil temperature. They wait for the right conditions for breeding, which are when the ground thaws to 65°F (18°C) in a brood’s designated year.

cicada exuvia

Do Cicadas harm humans?

They look big and creepy but adult cicadas do not feed from humans unless they are allowed to remain on someone long enough to mistake a part of the human body for a part of a plant.  There is concern for human hearing during these mass emersions of broods.   Experts say the piercing mating call of the 17-year cicadas, produced the males to attract females could be a harm to our hearing.  This sound is made from an organ called the tymbal.  The tymbal contains a series of ribs that buckle one after the other when the cicada flexes its muscles. Every time a rib buckles, the rib produces a click.  Many clicks produce a buzzing sound.  This buzzing sound has been measured at 90 decibels and higher.  That’s louder than a human conversation, louder than the noise of city traffic inside a car and almost as loud as a train whistle. According to federal health standards, noise louder than 85 decibels should not be heard for longer than four hours at a time.  And sustained exposure to noise at 90 to 95 decibels can result in hearing loss.  Please consider wearing ear plugs or protective ear phones while doing yard work during the mating of the cicadas.  Luckily, the time this noise is created is short and does not last indefinitely.

Many people are also concerned about the damage to the vegetation and what will be left when these insects finally finish their adult life cycle.

Periodical cicadas do not create destructive plagues, as locusts do, though as many as 1.5 million cicadas may crowd into a single acre. Unlike locusts, which are large grasshoppers, cicadas don’t eat vegetation but rather drink the sap from tree roots, twigs, and branches. Cicadas lack the mouth part that can chew and swallow vegetation. Cicadas drink rather than eat with their mouth parts (aka rostrum or beak) which are in the shape of a straw, piercing rootlets, roots and branches for a drink of Xylem (watered down sap).  Although cicadas do not eat vegetation, large swarms can overwhelm and damage young trees by feeding on the sap and laying eggs in them.  Perennials, annuals, tropicals and garden veggies are safe. It’s the woody plants that are at risk, with evergreens being their least favorite.

Females lay eggs in a V shaped slit they make in bark, preferring young branches that are about the thickness of a pencil and a bit stouter. Many of the branches will heal by forming calluses, but others won’t recover, especially if visited by many egg-laying cicadas. The vegetative growth above the injury will turn brown and die, a process called “flagging”.   Shrubs may take a hit, but their week branches work in their favor. The greater threat is to young ornamental and fruit trees that have been planted in the past two years or so because they are full of optimally sized branches important to the tree’s future shape and growth. Older trees usually escape without serious damage as cicadas don’t stick around for long. Adults die off within about four to six weeks after emerging.

Unwelcome guests?

There are many people who simply have a phobia of these large, noise making insects and prefer not to hide out in their homes for over a month until they expire.  It is understandable. Here are a few ways to humanely deter cicadas from your yard, in hopes of finding peace this coming spring:

  1. Attract natural predators to eat cicadas to control their population is an effective method that’s very safe.  Some species of birds love cicadas, which are a great source of protein. These species are specifically known for eating large numbers of cicadas in a feeding so be sure to place their favorite goodies out in your feeders to draw them in for natural pest control during the exposure of the brood, which begins in May of 2021.  Here in the Adirondacks, we will begin to see Brood X when the temperature rises to 65 degrees and higher.
  2. By handpicking adults and nymphs off plants by hand, if found in small enough numbers.
  3. Garden hose – Knocking cicadas off plants by spraying water with a garden hose.
  4. Foil & Barrier Tape – Wrapping tree trunks and large bushes with foil or sticky bands (barrier tape) to catch cicadas trying to move up plants to feed or lay eggs.
  5. Netting – Protecting young or valuable plants by covering them with netting.

There isn’t a part of the natural world that isn’t amazing, however we can take action to ensure that we continue to have positive interactions with the wonderful world we live in and all of its creatures.

Images courtesy of Jackie Woodcock

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Jackie Woodcock was born and lives in the Adirondack Mountains. She is an apiarist, lepidopterist, conservationist, teacher, writer, artist, and a co-owner of SkyLyfeADK. You can find her SkyLyfeADK on Instagram and Facebook.


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6 Responses

  1. Stan says:

    Obviously birds and many mammals will eat these things. Do you know of any record of humans foraging on them historically as they have on locusts?

  2. Tim says:

    Interesting bugs but they don’t appear in the Adirondacks on any of the maps I’ve seen. I wish.

  3. Craig says:

    The article states there are certain birds that eat cicada’ but you don’t say which birds we should try to lure into our yards. Could you please list the birds that will eat the cicadas.

  4. Joe Hansen says:

    Good article, I don’t why anyone would be bothered by periodic cicadas more than they would be enchanted by them. They are not beetles though, but true bugs.

  5. Mike Kerker says:

    Good article. Love cicadas, but they’re NOT beetles! They’re in the Order Hemiptera (true bugs), beetles are Coleoptera.

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