A size 10 fly originally tied to represent the stonefly lava. This style of pattern, as it’s name indicates, hails from the USA state of Montana, where it’s used on the Yellowstone and Missouri rivers. This tying of the pattern has a woven body, using black chenille and Firefly’s Lumi Foam to produce a different effect. The thorax region is formed using yellow chenille, with a black hackle wound through it. The big success for this pattern, in this country, is on the big reservoirs but it also produces on smaller stillwaters. Fish usually take this pattern out of aggression, so it tends to work all season.