Seventeen years ago near this season I was starting my second year as an arborist in training. A few months more into the year and I would be applying to the ISA to sit for the Certified Arborist examination, which thankfully I would pass. At this point in my career, I was fortunate to be working under a foreman who was (and is) passionate about trees, so as I learned primarily about climbing and pruning, I was also being taught about CODIT, tree identification, and common tree pests and diseases.

For those who mark time by political events, George W. Bush was president at the time, serving the first of what would be two consecutive terms.

Technologically, the first iPhone was still not to be available for another 3 years, so we were truly living in a different world. I think it was around this time that I purchased my first mobile telephone after stubbornly holding out for several years.

Ecologically, 2004 was the first year I directly experienced the effects of the 17-year cicada. Since then the world has turned and changed until the different cogs and wheels have aligned once more to allow the offspring of that very brood to emerge. As I sit and write this, the final instar (development stage) of those eggs that were laid 17 years ago are undergoing the last steps of maturation, soon to emerge as adults. I imagine them crawling up out of the ground, squinting at the sunlight (as they would if they had eyelids), crawling up a tree, a fence post, and going to sleep one last time. The sleep of pupation ends with an awakening into a new form. For 17 years these nymphs have been slowly growing, feeding on roots underground, changing mostly only in size. Now, something shifts inside and they decide to crawl into that great world above and go to sleep in the sun. And lo and behold, this time they awake as something very different. Who could have guessed that winged creatures would emerge from these slow, crawling, subsurface dwellers? They cast off the old husk of what they were and take to the sky, flying from tree to tree. The world aboveground has changed into something very different from what it was when these eggs were first laid. The changes that humans experience at times so tumultuously may have been experienced by these nymphs as distant rumblings or far off vibrations, or not at all.

What to expect

I have had several clients already ask me about the 17-year cicada, and what should be expected this season. Here is what I recall from my second year as an arborist:

1.
For the squeamish, these insects are a challenge. They are harmless, but they are large and very imposing. As less than graceful fliers, they can be startling when several of them fly into you if you walk past an infested tree. They make a buzzing sound as they fly, clumsily careening off of branches, arms, and faces.

2.
Also for the squeamish, despite the fact that they are harmless, they do not look so. I remember an insect with large clear wings, blackish body, and large, beady, red eyes.

3.
The 17-year cicada makes up for the fact that it is hardly ever around by emerging in large numbers. The noise made by the males as they sing for the females can be quite deafening and is mostly constant. One thinks that the females must be attracted not by the quality of the song, but by the male who can keep shrieking the longest. (And the “singing” is not really that – I imagine the sound is produced by rubbing body parts together similar to a cricket).

4.
The females use an ovipositor to cut slits into the outer twigs of trees, usually choosing twig growth from the previous year. Looking closely at these slits, the eggs are visible as whitish, elongated structures carefully lined up in the slit.

Cicada damage to a branch from a previous year

5.
This ovipositing can weaken the stem, causing it to break and hang off the tree. The leaves on the stem die, making the tree appear to have brown flags all over the canopy.

6.
Many times the twigs do not break off, but the wounding on the stem allows an opening for pathogens to enter the tree. I have seen sugar maples with cankers formed on each and every twig that had cicada oviposition, creating a very spectacular appearance in the tree.

I have also noted mature pear trees going into decline in the years following a cicada infestation – the declining growth can be traced back to the year the eggs were laid on the stem.

Regarding that last point – I always wondered if the decline was associated with some unknown pathogen vectored by the cicadas. Then I recently listened to a lecture by Dr. Klooster at OSU. She explained that in the final year prior to cicada adult emergence the nymphs were at their largest size, and fed most heavily on tree roots prior to emerging for their pupation into adults. Given the decline in trees that I had traced back to the year of oviposition, in my mind I correlated this heavy root feeding with an additional taxing of tree resources which could cause a temporary decline in the tree. This taxing of resources coupled with potential pathogen entry into the tree at the canopy and root level could definitely cause decline.

As tree owners, what do we do?

The trees I have noticed going into decline following a cicada infestation are thankfully few and far between. For the most part, mature trees deal with the issue quite well. Newly planted trees are another story. A tree that has been recently transplanted is already going through transplant stress. The added stress of twig damage and possible foliage loss from the ovipositing female can harm smaller trees. Given their size, these trees can be wrapped with netting to keep the cicadas from accessing the outer canopy. My wife was able to find a sale of material called tulle – it is a light netting that I hope to be able to use to wrap my younger trees to avoid most of the damage. If I am successful, this means that I will also avoid the first hatchling nymphs dropping into the soil below my trees and feeding on the tree roots for the next 17 years. My advice is to wait until the new leaves have hardened off and then use a light netting small enough to keep the cicadas out. Cover the tree canopy and monitor to make sure no adults are getting in. Once the cicadas are gone the netting can be removed. From what I recall it seemed like the cicadas emerged sometime in June and persisted for several weeks into the summer. I can state with confidence that if this brood is going to be a damaging presence in your landscape you will not be unaware of it.

In closing

In closing, I think of all the changes that have taken place since 2004. We are on our fifth presidential term since President Bush’s first term 17 years ago. Most of us now possess a smartphone of some kind, and spend a lot of time staring at it. In 2004 I never dreamed I would live through a pandemic! My hair has gone gray, and I have a lot less of it. A friend introduced me to an amazing woman who later agreed to become my wife. More than half of the time I have been part of the team at Russell Tree Experts.

Take stock for a moment. This is an interesting milestone. The 17-year cicadas may be an inconvenience, but the regularity of this brood (and there are several other broods that emerge at different time intervals) is actually quite fascinating. Why 17 years? And how 17 years? Who is counting for the insect? Theories abound, and other stories, but the rebellious part of me enjoys knowing that we don’t really know. In the meantime, I will sign off, wondering for a moment where I will be 17 years from now. Just think, it will be 2038. We will have gone through three or four more presidents after President Biden. Who knows what technology will be in our pockets? If I am not retired yet, I will be looking at retirement right in the face.

Go out and plant a tree this fall. In 17 years it will be big enough that you won’t have to worry about wrapping it with netting.

Nothing like a bit of perspective to balance your day. When the next 17-year cicada brood emerges, most of our current struggles will be almost all forgotten. I hope that serves to keep us from getting too worked up about some things we are going through today.

Your friendly neighborhood arborist, wishing you all the best,