Goldenrod Rosette Galls, Part 3

Last August I mentioned I was heading off to do some work in Maine and that I might bump into some more of the seaside goldenrod rosette galls that were only known from a single example I had collected on Nantucket.  Well, I conducted botanical surveys at nine different coastal properties, and at one–just a few miles from Canada–I did find a few.


I stuffed several in a bag, and as before, the adult midges started emerging by the next day.


Netta Dorchin was hoping to examine some larvae for her description of this new species, so I peeled open a few of the larval cells in one of the galls to see what I could find.  The first one had a ~2.5-mm peach-colored larva inside:


The next contained this 3-mm yellow one:


I wasn’t so sure these two were the same thing.  Was one of them an inquiline or parasitoid?  The next cell had a whitish larva:


And then another yellowish one:


A few hours later a second type of midge started appearing in the bag.  These were smaller and paler and behaved differently–they were more active and antsy to fly away–so I was pretty sure they belonged to another species.


A side by side comparison:


So I hoped I’d preserved a few of the right kind of larva, but I couldn’t be sure.  A couple of days later I pried open another larval cell, and I found this:


It was a midge pupa being eaten by a parasitoid larva.  The next one contained a similarly half-eaten pupa, but with a pale wasp pupa tucked inside it.


A few days later, adult pteromalid wasps started emerging.


On the same day, a third type of midge started emerging, even smaller than the second type, and with patterned wings.


I’m told this one is a predatory species, probably a Lestodiplosis.  Presumably that’s what this orange larva is:


And then there was this one–a male to go with the patterned-winged female:


From then on, every larval cell I opened had a wasp pupa in it, even though assorted midges kept emerging from the galls.



And just to round things out, a few eurytomid wasps emerged, possibly the same as the ones that came out of the Nantucket gall.


So I shipped off all the midges to Netta Dorchin, and she confirmed that I had in fact included some larvae and pupae of the gallmaker.  But earlier this month she reported back:

I’m afraid I have bad news regarding the Asphondylia species from Solidago sempervirens. I’ll include the information about it in my paper but won’t be able to describe it there. This is most probably a new species but the molecular data were unable to separate it from a population I have from Solidago bicolor from Virginia. The two populations are mixed together and I won’t be able to understand what’s going on there and how many species are involved until I have a bigger samples from both host plants for molecular study. I still have some of the midges you sent me in 2012 and can sequence them for this purpose but this will have to be done in a separate manuscript. It’s a pity but I hope this only means that the description will be delayed. Better to know the actual situation than describe species and then deal with taxonomic and nomenclatural changes.

So if you happen to come across these rosette galls on silverrod or seaside goldenrod, and feel like sending some of their contents off to Israel, you may be able to help get these species properly named.

…Oh, I forgot to mention that this caterpillar was living in one of the galls too. I wasn’t able to raise it.

Edit, 2/25/2013: Raymond J. Gagné informs me that the first two midges are probably the male and female of the Asphondylia species that caused the gall.  (I had considered this possibility, but hadn’t remembered seeing this dimorphism the first time around.)  “But the male and female adult predators could well be two different species.  Normally the male and female of a species have similarly patterned wings.”

About Charley Eiseman

I am a freelance naturalist, endlessly fascinated by the interconnections of all the living and nonliving things around me. I am the lead author of Tracks & Sign of Insects and Other Invertebrates (Stackpole Books, 2010), and continue to collect photographs and information on this subject. These days I am especially drawn to galls, leaf mines, and other plant-insect interactions.
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3 Responses to Goldenrod Rosette Galls, Part 3

  1. Annie Runyon says:

    This on-going story is wonderful! I really enjoy reading all of your posts. Thank you so much for sharing your explorations.

  2. ophis says:

    I think I photoed one of these galls on Martha’s Vineyard in mid-August five years ago:
    rosette gall (phyllody) on seaside goldenrod

    • Yup, that’s the one! I recently got an advance copy of Netta Dorchin’s goldenrod Asphondylia revision, and she decided not to name this one yet–it’s very similar to a species on silverrod (S. bicolor), and she needs more samples to determine how many species are involved and how they can be distinguished. (I guess this isn’t any new information, now that I just re-read this post.)

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