The flash of the brass bead has also proven to be very attractive to several other kinds of sport fish. Its possible that it just makes the fly easier for the fish to locate. Roman Moser states that the roots of the Gold Head or Pearl Head flies lie in the Northern Italian area. At the turn of the century the fishermen of Piemont, Bergamo, Brescia and Friulia fished in their alpine rivers with a bead headed nymph for spin fishing. The beads came from the glass making area of Murano (Venice). This type of nymph was then used by Roman in 1978 when the RM bottom downstream technique was born as shown in the video "New ways with the caddises and new ways with mayflies". Because the flies were light made of glass Roman experimented with Cabela's spinner bodies made of brass, goldheads were born.
Nobody understood this until he published the making of that Gold Head in the German magazine "Fliegenfischer" January/March issue 1985. The article was titled: "New ways of fishing the caddis". He found out that when sedge flies were hatching, the Gold Head was most successfull, possibly because the bead resembled the air bubble thorax of the natural nymph. [FULL ARTICLE]
The brass bead head fly has become one of the most popular fly types. This is because the weight of the brass bead helps keep the fly very close to the bottom where trout are used to seeing and capturing naturals. 
