There is a circa two thousand year old fly pattern that makes an excellent fake of the soldier beetle. It works as a caricature rather than an exact imitation but is seems to have all the stimuli necessary to convince the trout that it is indeed another of the nutritious beetles.
It is called the Red Hackle and it is a simple and fast fly to tie. You can have a dozen ready in twenty minutes or less so put a little time aside and make sure you have a few in readiness for the return of the soldier beetles.
You need red knitting wool (I use scarlet wool), natural red cock hackles, black thread and some hooks about size 12 or 10.
Put the hook in the vice as shewn. Run on a short bed of thread at the front of the hook
Tie in the cock hackle as shewn with six turns of thread. Snip off the waste hackle stalk.
Teeze out a small ball of red wool from a strand of the knitting wool and dub this onto the thread in a long thin sausage of wool.
Wind the body tightly down to the bend of the hook. If the amount of wool is guessed correctly it will all be used up when you reach the bend. Let the thread dangle here under the weight of the bobbin holder.
Take the hackle point in the hackle pliers and wind four to six tight, touching turns up to the start of the body. Then carry on winding down to the hook bend in open, spiralled ribbing turns. Tie in the hackle with a couple of tight , touching turns and then rib the body with the tying thread and wind the thread quickly through the front part of the hackle. Make a bold head with your whip finish and varnish it well. Use the waste hackle point to clear the varnish out of the hook eye whilst it is still wet.
Voila! The Red Hackle.
You can use this fly on fast rapids too. It shows up well and is another good "bring 'em up" fly. This might possibly be because it looks a good mouthful and so worth the effort of rising?