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May 21, 2016

Why do some cicadas have shriveled up or damaged wings?

Filed under: FAQs | Molting — Dan @ 5:00 pm

You might notice that some cicadas have shriveled-up or otherwise damaged wings. Most of the time, wings become damaged during the molting process (ecdysis), specifically while their wings harden (sclerotize). Their wings and body are most vulnerable when they are still soft.

Hang Time

Some reasons why a cicadas’s wings might not get the chance to inflate and harden:

  1. If a cicada molts and its wings are not able to hang downward they won’t inflate with fluids and form properly.
  2. Cicadas often trample each other in the rush to find a place on a tree to molt.
  3. Harsh weather, like wind and rain, knock them to the ground or bend their wings when they’re soft.
  4. Pesticides
  5. Malnutrition.
  6. Physical weakness or defects.
  7. Fungi infection.
  8. Predator attacks.


Reasons 1 and 2 are due to humans reducing cicada habitat (forests & fields) and replacing the habitat with buildings, streets, sidewalks, etc. Yes — you are the problem :). But — you are also the solution. The best paper on this is “Faulty Eclosion in Crowded Suburban Periodical Cicadas: Populations Out of Control” by JoAnn White; Monte Lloyd; Jerrold H. Zar (https://www.jstor.org/stable/1937659?seq=1).

Stuck

Just 10 Magicicada (American periodical cicadas) generations ago, the U.S. was mostly forest. Back then it was easy to find a vertical surface to molt on, or a plant stem to hang from. Today most forests have been replaced with agriculture, buildings, lawns, roads, sidewalks, parking lots, etcetera — so it has become increasingly difficult for periodical cicadas to find a good place to hang.

Magicicada can afford to lose a large number of their population due to wing malformations and other critical defects because there are simply so many of them — this loss falls in line with their predator satiation strategy.

However, if Magicicada cicadas lose too much habitat, they will go extinct (brood XI went extinct about 60 years ago). Lawns, roads, sidewalks, and other features of our human habitat create surfaces that are insalubrious for cicada molting.


Here’s a good photo by Jim Occi:

Adult Brood II Magicicada septendecim from Westfield NJ by Jim Occi


In the video below, you will see a cicada molting. Note that its wings are able to hang downward and inflate to form properly shaped wings. If the cicada tried to molt on a vertical surface, the odds are its wings would be crumpled.


In the image below, there is a Neotibicen tibicen (not a periodical cicada) that sclerotized (hardened) before completely shedding its nymphal skin.

Marvin. Didn't make it all the way out of its old skin. :(
Although adorable, this Neotibicen will never sing or fly.

24 Comments

  1. Lori says:

    I have one more question about the fungus. Some of the Magicicadas I’m seeing (especially Septendecim) has what looks like white powder on their backs. Could that be a light dose of the fungus?

    1. Dan says:

      Do you have a photo (send it to cicadamania@gmail.com)

  2. Sue says:

    I’m really enjoying the cicadas so far (Cincinnati), but it’s early in their appearance so I may grow tired of them by the end. I’m amazed how many come crawling out of grassy areas at dusk, just in time to find a vertical spot before predators find them. I have on occasion helped them find a tree or an appropriate space for them to molt. I’m curious why so many continue to physically move despite not having a whole body. It saddens me that these little guys have waited 17 years and some won’t even get to molt properly, or will get eaten by birds and squirrels before finding a partner.
    Once they emerge, they immediately struggle to find a vertical spot and begin to molt? How long after molting do they “mature” and begin to fly? And then how long until they start hoping for a mate? I notice as at dusk, they begin crawling up the sides of my garage, but by morning, most of them are gone, leaving their shells behind. I’m guessing as we sleep, they molt, “mature” and fly away? Seems so quick but they’ve been waiting 17 years so I guess it makes sense. My favorite thing is watching them molt. It’s really quite unbelievable. Nature at its best.

    1. Dan says:

      It usually takes more than a day before they can fly. They do molt at night and many of them climb up into the canopy of trees before you get to see them. There should be plenty closer to the ground for a few days as well.

  3. Ellen says:

    I live in Oxford Ohio and am concerned to be seeing so many cicadas with deformed and damaged wings on the ground and on the side of trees.
    Understand that the wings may be damaged moulting on the ground, but am seeing many on the sides of trees with stunted wings.
    But there certainly are many healthy ones….

  4. Lori says:

    A load of cicadas I’m seeing in Washington, DC (~50%) have wing deformations. Many of them seriously deformed. I’m also seeing a number of them with black-ish tipped wings. Is that due to the fungus?

    1. Dan says:

      Nope. That is due to humans reducing their habitat or maybe pesticides. Why do some cicadas have shriveled up or damaged wings?

  5. Amy L Tich says:

    I’ve seen several cicadas that are missing the back half of their bodies. Does that result from a fungus?

    1. Dan says:

      That’s correct. It’s this: Which fungus attacks Magicicadas? Massospora cicadina.

      They communicate it during mating.

    2. Carly Smith says:

      Hi Amy, where do you live? I’m a reporter in Dayton, Ohio and I’m working with an entomologist who is working to find out where these Cicadas are. Thanks!

      1. Nicole Antoni says:

        Hello Carly, I live in Cincinnati, Ohio and have noticed a lot of different deformities in the cicadas in my area this time around. Alot have fully developed wings and are not even able to fly, some are missing wings, parts and everything in between.

        1. Christopher wood says:

          They can’t fly for a few days after molting

      2. Melissa N Morris says:

        Hello,
        I live in Berkeley Heights. It is located off Dorothy Lane just after Community Golf course. We have a large population of cicada.

        1. Dan says:

          New Jersey?! Fantastic!

        2. Sabine says:

          Hi, I was planning to go with my husband to the New Brunswick/Princeton area this weekend. Do you know if the cicadas also emerge with the rain and wet days? If you have recommendations or contact where to find them, please feel free to contact me. Thank you.

          1. Dan says:

            There’s none in the New Brunswick area but Plenty in Princeton. You won’t hear them sing on cold/wet days, but there are thousands hanging from trees, weeds and other plants at places like the Princeton Battleground Memorial park.

  6. Lori says:

    I’ve noticed that some of the nymphs are emerging in the yellow, shriveled state (as tenerals), but others are emerging from their exoskeletons already in the fully hardened black form. Why is this? It’s like they’ve matured inside the exoskeleton before emerging. I imagine this might be one cause for the wing and other deformations but am trying to understand why this is happening in the first place.

    1. John says:

      Lori, I think the black ones you are seeing are not coming out of the exoskeleton they are standing on but previously molted from somewhere else. The issues described with vertical molting are not happening here, the nymph emerge hanging backward and downward (like doing a backflip off a diving board) and their wings inflate properly. We reach that nymphs (molting mostly at night – likely a predator strategy) are the most tender for eating, some likened them to shrimp. We collected a bunch, popped them in the freezer for about 5 minutes, then into a hot pan with a bit of EVOO and pepper flake. They take on the flavors of what they are cooked in and don’t really have a flavor or much texture of their own.

      1. Lori says:

        Thank you, John. Is there any way I can send you a picture of this strange molting process I think I’m seeing? About the problems with the wings, at least half of the adults I am seeing have deformed wings.

        1. Joan says:

          I’m seeing this also in our local park in Princeton, NJ. It seems like I see more cicadas with wing deformation and abnormal molting on Ash trees that have been injected with pesticides to kill the Emerald Ash Borer. Other molting sites in the park have considerably less deformed cicadas.
          The ash trees have injection points at the base of the trunk where the roots begin. I’m curious if others are seeing this as well.

          1. Dan says:

            That could be it. A lot of pesticides do not discriminate. If you have any examples of elm trees with lots of shriveled cicadas, and it’s publically accessible, send me the location via email cicadamania@gmail.com. I will be discrete.

  7. Andrew Banham says:

    In the video description, it says;

    ‘In the video below, you will see a cicada moulting. Note that its wings are able to hang downward and inflate to form properly shaped wings. If the cicada tried to moult on a vertical surface, the odds are its wings would be crumpled’

    Does that mean if the cicada emerges on a vertical surface, but nose down? Or should it be ‘If the cicada tried to moult on a horizontal surface’?

    1. Dan says:

      Depends on the species, but generally they molt on a vertical surface (side of tree), or hanging from one parallel to the ground. If the wings cannot hang, they’ll get crumpled. When cicadas try to molt on the ground, like a sidewalk, the wings cannot hang, so they get crumpled.

  8. Dave says:

    Good summary and ideas.

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