The Green Drake Parawulff may seem like a monstrosity of a mayfly pattern…but that is just to imitate the real thing. The Green Drake is Colorado’s biggest mayfly that hatches throughout the state in June and July. The Rio Grande, Colorado, Frying Pan, and Roaring Fork are a few rivers that have incredible Green Drake hatches. When these bugs are coming off the water; you do not want to be without a few drake patterns in your box. Trout tend to go haywire for these mayflies.