The large pincers show it is a male; they are used for grasping the female.For comparison, here is a female, with smaller pincers- <a href="http://www.allposters.es/-sp/Female-Dobson-Fly-Corydalus-Cornutus-Posters_i6264345_.htm">http://www.allposters.es/-sp/Female-Dobson-Fly-Corydalus-Cornutus-Posters_i6264345_.htm</a> Good to have a familiar object for scale in your photo, Sam; thanks.But here is a photo perhaps giving a better idea of its size!http://carnivoraforum.com/topic/9673475/1/ http://en.wi