Yesterday I found another dead Brood X cicada on our front porch. It has been 12 days since I saw the last one. In recent weeks, the sudden stop of the loud buzzing created by billions of cicadas in 15 Eastern states saddened me. Baltimore County residents who were upset by the din, (which often reached an earsplitting level of 105.9 decibels), felt only relief.
Male cicadas vibrate their tymbals, located on each side of their abdomens, to generate mating noises also known as Crepitation. Females can hear their suitors as far as a mile away. The modern English term of cicada is derived from the Latin word cicada, meaning “buzzer.” The term itself is an onomatopoeia, or a word that mimics the buzzing sound the male insect makes. Females emit a less noisy ticking sound.
In June, 2021, one and a half million cicadas per acre emerged from the ground in Baltimore County as juvenile nymphs.
Images above are of cicada emergence holes and an exoskeleton. (More on exoskeletons: Prevention, Why Do Cicadas Molt? May, 2021)
After they transform into adults with wings, cicadas discard their final molts, a hard shell known as an exoskeleton that supports the insects in various stages of growth. They then search for a mate. (Read this informative article about Brood X’s life cycle and view the beautiful illustrations in Scientific American).
These days I miss the sights and sounds of these beautiful creatures. For six weeks, scores of males and females buzzed and flew around like drunken sailors on leave, and landing wherever their weak silvery, orange-rimmed wings led them, at times only on asphalt.
The YouTube video below records the 17 year cicadas sounds in groups and individually. In one instance, the narrator is wrong in stating that cicada eggs are laid in the ground. Female ovipositors lay them in tree branches, but the rest of this short video is accurate.
After they emerged, I caught a number of these strange insects on driveways and streets (and on my neck, face, and body), and gently placed them on tree branches or trunks to help them fulfill their destiny. Many in my family were not as equally enamored and swatted them away. Some people suffering from entomophobia were truly scared of them. [Fear of cicadas is real and common. It’s also far from unfounded. Washington Post].
There are 7 species of periodical cicadas, one was recently described. There are 3 species in the Washington, DC area. There are also annual cicada species (that are green) that come out every year.” National Park Service (NPS)
During an outdoor Forestry Board meeting in the second week of June, our group’s discussions could hardly be heard above the din of the male insects. Linda B, one of our board members, explained that cicadas drowned out the voices of other mating creatures, such as birds and frogs, prompting them to also raise the volume of their calls. I especially adored the loud croaking bullfrogs.
The Cicada Cycle
The birth-to-death cycle of the cicada Brood X is a miracle of nature. After the insects emerged in late May/early June, they provided abundant, protein rich meals for the creatures who ate them. Our birds, foxes, snakes, ants, raccoons, pets, and similar opportunists must have sated themselves on a seemingly endless buffet. This phenomenon is known as predator satiation. Usually predators are not too finicky when catching prey, but during this sumptuous feasting period, many only ate bits and pieces before gorging on another cicada body.
[Images of body parts left by predators. From left to right: click on bottom of image to read the caption or click on an image to view a slide show.]
Cicada emergence came in defined stages:
“The perception is once they come up, you get a big number. And as they start to go away, you think it’s over, then here it comes again like a tsunami…But one species will arrive in big numbers first, another in the middle and a third toward the end.” Insights, OSU.edu
Currently, scientists can only make educated guesses on how climate change will affect their behavior or their overwhelming quantities in the future. Still, the cicadas’ enormous numbers ensured that enough survived to mate and lay eggs to reemerge in the billions in 2038.
Cicadas generally don’t damage mature trees extensively. After mating, female cicadas use their ovipositors to cut slits in tender branches to deposit their eggs. This link leads to a photo by M.J.Raupp of cicada eggs hatching in a branch slit.
Flagging occurs when, after mating, females deposit their eggs through an ovipositor that gouges slits in branches in which they deposit their eggs. She lays from 200-400 eggs per hole. The nymphs hatch after six weeks before falling to the ground.
Twigs with many slits often break or hang down from trees, a condition known as flagging.
Leaves on the affected branches turn brown, a tell tale sign, but younger trees may completely succumb to the devastation unless protected.
One could think of flagging as nature’s way of pruning mature trees. Young saplings might be overwhelmed because their tender branches are more susceptible to the damage caused by the female’s ovipositors. (Read this article from the Master Gardeners of Northern Virginia: Managing Cicada Damage to Trees).
Hover your cursor over both images above to read descriptions.
Flagging image from UMD https://extension.umd.edu/resource/cicadas
“The phenomenon is known as “flagging.” It’s especially prominent in oak and beech trees, many of which now have brown clusters of dead leaves dotting their canopies. In most trees it’s completely harmless.” NPR- Brood X Cicadas Are Gone, But Their Eggs Will Hatch Soon And Rain Nymphs From Trees, July 6, 2021
“In many cases, the patchiness of the emergence has to do with females being choosy about which habitat to lay eggs in. Lill says they appear to prefer areas with full sun exposure, especially forest edges. – NPR
“Cicadas have been known to lay eggs on over 200 types of trees to some extent. Some common trees that are most susceptible to cicada damage include oaks (Quercus), maples (Acer), cherry (Prunus), and other fruit trees, hawthorn (Crataegus), and redbud (Cercis). Evergreens are rarely used for egg laying.” – University of Maryland Extension, UMD.edu
Some cicadas prefer maple, oak, hickory, beech, ash, willow, dogwood, hawthorn, magnolia, apple, pear, peach and cherry as host trees.- Ohio State extension
The photo example above is of a Magicicada septendecula, the cicada species (Brood X) commonly found in Baltimore County, which has thin orange stripes on the underside of its abdomen. This was the last cicada I found in my yard, dead, but not yet eaten. This image is of a female: note the point at the end of her abdomen. Her ovipositor is retracted.
Around six weeks after eggs are deposited in branch slits, cicada nymphs drop to the ground and burrow into the soil, where they feed off tree sap for sustenance underground until reemergence. seventeen years later. During this crucial time, the public should not remove flags that have fallen into their yards and woods until mid-August to allow the maximum number of cicada nymphs to burrow.
- Brood X Cicadas Are Emerging At Last, Scientific American, May 10, 2021
Excellent drawings and explanation of the lifecycle and identification of Brood X periodical cicadas.
- Cicadas: Tree Insects, University of Maryland Extension, July 7, 2021
Another great, scientific website about cicadas with photographic images.
- Cicada Mania, A website dedicated to cicadas, July 23, 2021
This website should please children and those who want to know more about these wondrous insects.
- How to tell male from female brood cicadas: Click here to read Bug of the Week on “How to tell the guys from the gals”.
- Google search images of cicada ovipositors