They are fish catches
I am no expert as I am only just starting off tying . A thing I was shown is before you tie in the wing get your Velcro to the fly and work some of the body out into the hackle and brush backwards towards the ar$e end of the fly to soften the hackle . I use my fingers to really get all them hackles going back . It really improves the look of the fly .
I also use the paired slip method that mayflyjunky said about , but then it was him that showed me how to roll a fly
That said though he showed me a few ways of doing the wing and I tried them all , I found in the end though I favour the paired slip .
Good luck and look forward to seeing the next ones