Europe’s heaviest fly: A gentle giant in Sweden’s Järfälla nature reserve

The dark giant horse fly (Tabanus sudeticus) is the heaviest fly species in Europe, growing up to 30 millimeters long—roughly the size of a queen bumblebee. Its heavy, muscular wings create a distinct, deep buzzing drone in flight, and unlike many other horseflies, its large eyes are a uniform dark brown rather than brightly patterned. While females require blood meals to develop their eggs—typically targeting large livestock rather than humans—males are entirely harmless nectar feeders. The sexes are easily distinguished by their eyes: females have a visible gap between them, while males’ eyes meet at the top of the head. I encountered an enormous male resting along the edge of a post-glacial lake in Sweden’s Västra Järvafältets nature reserve. I was surprised to see such an enormous fly casually walking across tall grass, and licking water and nectar from the foliage. Observing this gentle giant made me reconsider a childhood grudge sparked by painful horsefly bites.

Leave a Comment

Your email address will not be published. Required fields are marked *

Latest posts of related arthropods

Photo taken on 06-07-2025 in Serock, Poland, with the Nikon Z6-II camera and Nikon Z MC 105mm f2.8 VR S lens and following settings:  f22, 1/200, ISO 320.
From Poland to Sweden: Meeting Europe’s ...
Photo taken on 19-09-2026 in Husby, Sweden, with the Nikon Z6-II camera and Nikon Z MC 105mm f2.8 VR S lens and following settings:  f14, 1/125, ISO 250.
Tiny meadow gems: The world of Calliopum...
Photo taken on 12-09-2026 in Akalla, Sweden, with the Nikon Z6-II camera and Nikon Z MC 105mm f2.8 VR S lens and following settings: f16, 1/50, ISO 250.
Awl tails and orange stockings: Meeting ...
Photo taken on 12-09-2026 in Barkarby, Sweden, with the Nikon Z6-II camera and Nikon Z MC 105mm f2.8 VR S lens and following settings: f13, 1/50, ISO 250.
Vibrant orange and folded wings: Meeting...
Photo taken on 12-09-2026 in Barkarby, Sweden, with the Nikon Z6-II camera and Nikon Z MC 105mm f2.8 VR S lens and following settings: f10, 1/40, ISO 250.
Microscopic eye fuzz and underwater hunt...
Photo taken on 04-06-2026 in Alvkarleby, Sweden, with the Nikon Z6-II camera and Nikon Z MC 105mm f2.8 VR S lens and following settings:  f14, 1/200, ISO 250.
The truffle hunter: Meeting the mushroom...
Scroll to Top

Would you prefer to hide close-up spider photos?
Wolisz ukryć zdjęcia pająków?
¿Ocultar fotos de arañas en primer plano?