Queens Award for Voluntary Service

Dark Giant Horsefly


I shared a bench overlooking Hay Meadow with the Dark Giant Horsefly on Monday. These flies are huge (25mm long) and apparently the heaviest flies in Europe. This one is female (her eyes don’t meet unlike the males) – not good news as she is the one that feeds on blood, though only just before she lays eggs fortunately; otherwise she feeds on nectar like the males.  Thankfully she prefers the blood of cattle and ponies – watch out White Parks!  Humans are sometimes bitten, though, and can have a severe reaction).  Dark Giant Horseflies are not that common, mainly occurring in boggy areas in the north and west of Britain, so right at home in Fairfield Reserve.  They fly in July and August.


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1 thought on “Dark Giant Horsefly”

  1. Hi Jen
    Great to see you posing on the blog. I was bitten by something in my garden but I don’t think it was a giant one .
    Could you select Wildlife as a category when you post – it’s easier when I trawl the blog for an annual report of sightings


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