This one made a summer night visit to the room and tried to escape by banging against the ceiling. What is it? I found nothing which corresponds, though "horse fly" might be a close match.

  • Location: Central Europe, Luxembourg
  • Locality: Where the suburb morphs into the not-yet-conquered countryside
  • Time: Late August, Nighttime
  • Weather: Quite warm (~27°C). Dry.

Here is an MP4 of the beast: https://i.imgur.com/F5yqMQ8.mp4

It is about 2 cm (0.8 inch) large. Relatively plump, keels over and likes to clean itself a lot.

unknown fly 1

Large head, large eyes, a bit hairy, two black stripes

unknown fly 2

Once it falls on its back it wallows a bit, there is clearly a probabilistic algorithm to get itself out of the predicament:

unknown fly, wallowing

  • $\begingroup$ @BryanKrause Thanks Bryan. I have added some info. And a link to an MP4 $\endgroup$ Aug 28, 2019 at 7:47
  • 2
    $\begingroup$ Its not a horsefly (Tabanidae), but rather, a flower fly (Syrphidae). I don't know what species. $\endgroup$
    – Karl Kjer
    Aug 28, 2019 at 10:38

1 Answer 1


At first, because of the size and shape, I thought that it was a horsefly, but no horsefly looks like that (at least not in Luxembourg). It turns out that it was a hoverfly, just as Karl Kjer said. The species is Volucella zonaria, or the hornet mimic hoverfly. This hoverfly lives in most of Europe (including Luxembourg) and is 15-25 mm in length, consistent with your 20 mm estimate.

In this image you can see the same coloration and abdominal markings as your insect.

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The markings in your photo are very difficult to see but are there.

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Wikipedia page

original image source

  • $\begingroup$ Thanks. I had forgotten about that question. Good id. $\endgroup$ May 26, 2020 at 6:13

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