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Hello!

There were thousands of Mikiola fagi flying around in the forest this afternoon (northwest Germany). But this Cecidomyiid was only 2.5 mm long, half the size as M. fagi. And it was ovipositing at an oak log (why at the log of a cut tree? Aren't Cecicomyids breeding in leaf galls?).

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Pic #2

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Pic #3

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The Cecidomyiidae ovipositing into cut surfaces of oak are female Xylodiplosis. This genus is well known in Europe and North America although relatively little information has been published. The remarkably narrow and elongate larvae live within xylem vessels, usually in freshly cut or recently broken live wood. The long, telescopic ovipositor, visible in these photographs, is presumably an adaptation fo r placing eggs precisely into the xylem vessels. Adults are active early in the year and there are at least two European species : X. aestevalis and X.nigritarsis. I have seen females ovipositing in Italy (Tuscany) in February. Cecidomyiidae have remarkably diverse biology. Many species are phytophagous (including gall inducers) but others are mycophagous or zoophagous (including predaceous and even endoparasitic species).

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Hello, Orseolia!

Many thanks for your very interesting informations! I knew that Cecidomyiids have a diverse biology, not only producing galls, but even parasitoid or predatory. But I never read of this way.




In my "Entomofauna germanica" (1999) there is only nigritarsis listed for Germany.

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Yes, according to Gegne's World Catalog of Cecidomyiidae (now available on-line) X. aestivalis has only been recorded from France whereas X. nigritarsis has been reorded from the UK, Denmark, Netherlands, France, Germany and Finland.