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June 26, 2016

Got Flagging? Report flagging and egg nests.

Filed under: Community Science | Flagging | Magicicada | Ovipositing | Periodical — Dan @ 1:01 am

Got flagging? Flagging happens when tree branches wilt or die due to cicada egg laying, resulting in bunches of brown leaves. Don’t worry, this will not cause trees to die, unless they are small and weak trees. Flagging can actually do a tree a favor, by removing its weakest branches.

Some video of cicada flagging:

A photo of flagging:

Periodical Cicada Flagging


  1. I live in Baton Rouge, La. Where can I see trees like the ones showned on this site…

  2. Jennifer Rothschild says:

    I have seen the residue on my driveway, beneath a Norway Spruce tree.

    1. Dan says:

      That makes sense then. It is probably sap from their egg nests. The sad thing is periodical cicada eggs typically don’t take when they’re laid in evergreen branches.

  3. Jennifer Rothschild says:

    I am told that the oily residue that is now being seen around here, is somehow connected to the cicadas. Their peak period is definitely over here, and there is no hum in the air anymore. What is this residue?

    1. Dan says:

      It sounds like tree sap from when they build egg nests in branches. What kind of trees does it appear near?

  4. kathy says:

    I dont hear or see the cicada anymore does that mean they are gone in my area in edison

    1. Dan says:

      That’s right. They’re gone.

  5. kathy says:

    I dont see or here the cicada anymore does that mean they are gone for good in edison

  6. Gina says:

    I live in Rahway, NJ (07065). Some of the towns/cities surrounding me have cicadas. My town has not been hit yet.

    1. Is there a possibility that we won’t experience them -at all?
    2. I understood they came out at about the same time in regions, when the ground reaches a temperature of 65 degrees. Can we expect a late (July or August) surge?
    3. There are NO regular cicadas this year – which is great, as I hate the loud, eery screeching, particularly as the humidity rises. Are “regular” cicadas affected by the 17-year cicadas?

    1. Dan says:


      I you haven’t seen (or heard) any yet, you probably won’t. They (for better or worse) aren’t found everywhere, and Rahway might be a dead spot for them. There were plenty in Avenel though, so there probably were a few on the borders of the town. Generally development, pesticides and the pressures of a city-like area kill of cicada populations.

  7. barbara lindemann says:

    there are also a lot of cicadas in the watchung reservation. Take rt 78 west to exit 41, scotch plains and Berkeley heights, and drive towards rt 22. There are lots of scenic woodsy places to stop for cicadas along the way. I grew up in this part of northern nj and I remember the mass emergence of 1962!!! These are the descendents of “my” childhood cicadas:) there’s also Trailside museum in watchung that would probably have a lot of current local info, plus trails to explore in search of cicada data . They also have a nature center:)

  8. barbara lindemann says:

    I was just at my brother’s house in scotch plains, nj. He lives near Brookside Park, which had a mass emergence a few weeks ago and is still very noisy! Cicadas everywhere! Climbing the trees, falling out of the sky and landing on the picnic table, lots of shed exoskeletons around the base of trees… Also flagging especially in oak trees. Interestingly my brother said that after a recent storm, there were a lot of small branches on the ground. My theory is that the slits for laying eggs weakens the branch tips so they break off, thus enabling the newly hatched nymphs to safely burrow into the ground. This seems more adaptive than hatching high up and falling, although this would allow some to travel much farther than the parent tree. Perhaps cicadas utilize both survival strategies.

  9. Chris Simon says:

    Thanks Dan! This is excellent. Knowing where there are areas of heavy flagging will help us track the most dense populations of periodical cicadas and could be places where it will be easy to find cicada nymphs in the future.

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