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Still have them...

Found this info:
«Pegohylemyia jacobaeae Ragwort seed fly (Anthomyiidae)
Larvae predatory on other fly larvae in flower heads of Senecio erucifolius & S. jacobaea. [genus may be cited as Botanophila]

Pegohylemyia seneciella (fly, Anthomyiidae)
Larvae in flower heads of Senecio jacobaea, producing a cone of froth, which dries, in the middle of the flower. Found where Ragwort plants are few; in large stands there is greater probability of predation by Pegohylemyia jacobaea.»

in http://www.buglife.org.uk/conservation/currentprojects/Habitats+Action/Ragwort/ragwortfactfile

(Fauna Europaea uses «Botanophila»)
Bart