I have been experimenting with running a trailer fly 3 feet behind my steelhead Jigs. The main result is that if I am using the jig they want, they will hit that before hitting a trailer. Last time out was a tough day but I did hook a steelhead and a brown trout on the Nuke Minnow Fly shown in the picture they both got off but I am sure they were on the trailer fly. I was running it behind experimental jigs I had low expectations for and fish hardly ever get off when hooked on a jig.
The hopeful advantage of the foam head flies is that I won't have to raise my jig up 6 inches higher than I want to fish it in order to keep the trailer fly out of trouble snagging the bottom. The foam head gives the fly a unique look and maybe some interesting action.
For what it is worth here is how to tie them. It is mostly the same as tying any fly except leave yourself a little bit of head space to tie in the foam head. For tying in foam this way, the width of the foam strip you cut will relate to the hook gap and use a thickness (2mm or 3mm usually) of foam right for the size of fly you are tying.
The Leggy Fox and the Nuke Minnow have been very effective as a 1/32 ounce #6 jig. The Leggy Fox Jig is a fairly bulky tie so we will tie this fly bulky on not too heavy a hook so it can stay off the bottom.
Twist the noodle tighter, then dub a bump to backstop the rear rubber legs.
Always leave the 2 forward legs in a loop until the very end. The loop does a good job of not tangling with the other tying steps. I tied each leg in separately: near back leg against the dubbing bump, near front leg on the side of the hook, far front leg on the back side of the hook in a loop, back far leg back against the dubbing bump.
This is plenty of head space. It would work fine with half this much head space.
I use a sharp knife to cut the foam into strips using a straight edge. Then by free hand I cut the back edge of the foam at an bevel angle while laying the foam down on wood or plastic. The bevel is on the bottom side of the foam strip.
Three thread wraps to get the foam in place behind the eye, then 7 more wraps to get it down securely. It is best to lift the forward foam and put the whip finish in front of it, around-behind the hook eye only. Cut the foam off close after tying off.
What the fish think this pattern is when it is tied on a jig hook is probably the wrong question. Lots of other fishermen have been having good days on similar dark brown, rubber leg jig patterns. They just have been hitting it well for me in March, then in October through December. If other fishermen are to be believed, it could work in any season.
The Black Stonefly Jig can be effective in February or March when stone flies are hatching. If you see a couple flying over the water, try a small black fly. It works well for me tied small and slim on a 1/64 ounce jig. This Stone Fly came out bulkier than I would like. Maybe next batch will be thinner.
I hope to have some fish pictures to show off here soon.