For a fly this size, you could use ultra chenille or one of those pre-made extended bodies, but for the bigger stuff like skwalas, goldens or salmonflies, the chenille wouldn't be big enough and these are kinda fun to make so why not? Just have to find the right platform for the plus size stones; I'm thinking plastic golf tees.
hook - Dai Riki 135 #16
thread/rib - UTC 70 hopper yellow
abdomen - extended body (DIY used here)
thread
GE Bath and Tub silicone
Congo Hair pale yellow
Stalcup Microfine Dubbing pale yellow
wing - deer hair bleached
hackle - light ginger
Part 1
There's a few different ways to make the body; here's one that's worked pretty well for me
place needle in vise and coat with wax (Mucilin used here)
start thread
tie in some Congo Hair strands (or whatever synth yarn you care to use); keep it sparse
cover with thread and trim
insert needle into a tube of silicone and coat
pull out some dubbing (longer-fibered synth stuff works best for me), let it touch needle and start rotating to create body; if you don't have a rotary vise, a variable speed drill works fine