The Brown Drake hatch is an absolutely terrific mayfly hatch for fly fisherman when you catch it right. Brown drakes are the first of the large burrowing nymphs to hatch in June on the northern Wisconsin freestone trout streams and trout love to stuff themselves on these large brown mayflies! The hatches can be very dense, but unfortunately do not last for many days.
The scientific name for the Brown Drake mayflies is Ephemera simulans. These large mayfly nymphs burrow in the sand and silt bottoms in the slower stretches of the trout streams. In June, at around dusk the nymphs emerge from their burrows and begin to wiggle towards the surface. Once at the surface they emerge slowly and ride the water for some time before being able to fly away to the trees and shrubs nearby. During this time they are extremely vunerable to feeding trout. As they struggle and flounder on the surface trying to escape their nymphal shuck their wings look like a mess and offer trout an easy meal.
Sizes range from #10 to #8 and my favorite pattern is an extended body comparadun (see: Brown Drake Fly Patterns). It is advisable to carry nymphs, emergers, duns and spinner patterns. Since this hatch generally occurs near dusk, it is often combined with the brown drake spinners coming back on the water to lay their eggs and die. Close observation can help you determine whether trout are sipping in the spinners rather than the brown drake emergers or duns. Be aware on cloudy days the hatch may occur in late afternoon or early evening.
Note: Since the Brown Drake hatch generally occurs in the evening size, silhouette and presentation are far more important than matching the exact color of this mayfly.
Video of Brown Drake spinnerfall on a Northern Wisconson trout stream