Currant galls on oak - geograph.org.uk - 1336489
They are caused by a Cynipid wasp, Neuroterus quercusbaccarum.
With such gall wasps, there is often an alternation of generations: one generation consists of males and females, and reproduces sexually; the other consists only of agamic females (i.e., they are able to produce offspring without mating).
The agamic females lay their eggs within the tissues of the oak, causing these currant galls to appear. The wasps that develop within the galls, and which later emerge from them, are a sexual generation of males and females; the mated females of that generation in turn lay their eggs in oak tissue, causing another kind of gall: 929354. A generation of agamic female wasps develop within and emerge from common spangle galls, and the cycle begins again.Relevante Bilder
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Neuroterus quercusbaccarumNeuroterus quercusbaccarum ist eine Art der Gallwespen (Cynipidae). Sie lebt überwiegend in Europa und Nordamerika und entwickelt sich wie die meisten Gallwespen an Eichen, wobei sie typische Gallen an der Unterseite der Eichenblätter bildet. Die Art weist einen Generationswechsel auf. In ihrem Lebenszyklus gibt es zwei unterschiedliche Generationen, deren Gallen sich stark voneinander unterscheiden. .. weiterlesen