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Many of the Common tansies (Tanacetum vulgare) in Brussels right now (http://observatio...w/56858471) have flowerheads like those pictures:


and some of them have also this sticky brown fluid in it:


galls of Ozirhincus tanaceti ?

thanks,
Bart

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I don't think the pale florets in the middle of the capitulae or the brown fluid are related to Ozirhincus tanaceti. However there are many galls on several of the capitulae in the first image and at least 5 in the left-hand capitula in the second photo (one at 6 o'clock 2 florets in from the edge, one at 10 o'clock on the edge, two at 11 o'clock on the edge, and one at 1 o'clock on the edge.

To see the galls split the flower head in half: the galled florets are considerably expanded in the lower part and should contain an orange larva. Manipulating the galls to expose the larva gives one a real feel for the robustness of the gall tissue.