Because caddisflies tend to emerge very quickly, trout don’t want to expend too much energy chasing them. Instead, the fish focus on those emergers that are crippled or are struggling to escape the nymphal shuck. The X-Caddis, developed by famed West Yellowstone guide and shop-owner Craig Mathews, imitates just such an insect, with a trailing shuck of Zelon and a splayed wing of deer hair. Because there’s no hackle, the X-Caddis sits very low in the water, as if the bug is trapped in the surface film. All of these features make the fly attractive to feeding trout, and the pattern has proven itself effective over the years.