The Trico Mayfly (Tricorythodes Minutus) vary in size from #18 to #24. Males emerge in the evening, and spend the night in a local shrub along the river. Females hatch in the morning, and become spinners within several hours. While the females hatch, the males molt into spinners, forming a massive cloud of flying trout food. Trout will begin to feed on these tiny mayflies as they fall to the water, the females to lay eggs, the males, spent. The trick to catching fish during the trico hatch is to cast your fly in the exact feeding lane of a trout. Because of the sheer abundance of available food, rising trout will seldom move laterally to eat. Use 6x or smaller tippet.