More Information, but still a Mystery

On my last post I found what I thought was some kind of pseudo-flower on Canada goldenrod.  Actually, I found out a little more about what was going on, but still ended up with a mystery.

What I found was called a goldenrod bunch gall, or goldenrod rosette gall.  It is caused by a tiny fly, Rhopalomyin solidaginis.  There are a number of different kinds of galls found on the many species of goldenrod, and each have a number of insects  associated with them.  This is a more typical bunch gall:


I walked around in the prairie and by the edges of the road.  All of the vegetation is very dry.  I was able to find a few more bunch galls.  Most did not have the white center, although I did find one other plant that had one bunch gall with a white center.


So the gall itself is caused by the fly.  But what causes the white center?  I am still thinking fungus spores.


About the roused bear

Nature photographer from central Iowa.
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One Response to More Information, but still a Mystery

  1. Margaret Bailey says:

    Did you notice any small white flecks on the plant near and. Around the white center? Did it have a cobwebby appearance? There is a sucking insect called white fly that can make an impressive wad of white soft webby stuff. If you poke around in it you may see some small aphid like insects.
    You probably already know this given your amazing knowledge of insects but it was worth mentioning!
    M. Bailey

    PS. I love your photographs! Thanks for sharing them!

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