This odd looking fly was sitting on an iris leaf in my back garden. It appears to have a horn! Is that right?
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It's a robberfly, probably in the genus Dioctria. They usually prey on other small flies.
The "horn" that you can see is actually one of its antennae. They hold them in a 'Y' shape, parallel near the head, then diverging. You can make both antennae out on the photo if you look closely, a bit like a catapult stuck to the front of its head! :-)
That's really interesting! Thanks for the education! :)
Lat/Lng: 50.8, -1.5
OS grid ref: SU4005