The Bow River and the PMD Hatch: A Detailed Guide for Fly Fishing Enthusiasts

When it comes to local trout fisheries, few events are as eagerly anticipated as the Pale Morning Dun (PMD) hatch. This hatch provides some of the most exciting and productive fly fishing opportunities, drawing in both novice and expert anglers. In this blog post, we'll delve into the details of the PMD hatch, exploring what makes it special, and suggesting some effective fly patterns for different stages of the hatch.
Understanding the PMD HatchThe Pale Morning Dun (Ephemerella inermis and Ephemerella infrequens) is a small, mayfly species that is prevalent in many trout streams across North America. These insects are typically pale yellow to light green, making them a standout on the water during their hatching periods. PMDs are most active during the late spring to early fall, with peak activity in June and July.
The Lifecycle of PMDsUnderstanding the lifecycle of PMDs is crucial for effective fly fishing:

1. Nymph Stage: PMD nymphs are generally light brown to olive and are found in the substrate of rivers and streams.
2. Emerger Stage: As they prepare to hatch, nymphs swim to the surface, where they emerge from their nymphal shuck.
3. Dun Stage: Newly emerged duns have upright wings and drift on the surface until they fly off to nearby vegetation.
4. Spinner Stage: After mating, female PMDs return to the water to lay eggs and die, often forming spinner falls that create significant feeding opportunities for trout.

Prime Times and Conditions for PMD HatchesPMDs typically hatch in the late morning to early afternoon. However, local conditions such as water temperature and weather can influence the timing. Overcast days can prolong the hatch, providing longer windows of opportunity for anglers. Water temperatures between 55°F and 65°F are ideal for PMD activity.
Effective Fly Patterns for PMD HatchesTo maximize your success during a PMD hatch, it's essential to have a variety of fly patterns that mimic the different stages of the mayfly's lifecycle. Here are some recommendations:

1. Nymph Stage Patterns:
   
   • PMD Nymph: A simple yet effective pattern that mimics the nymphal stage. Look for sizes 14-18.
   • Split Case PMD Nymph: This pattern has a realistic look and is particularly effective just before the hatch.
2. Emerger Stage Patterns:
   
   • PMD Emerger: Designed to imitate the insect as it breaks through the surface film. Sizes 16-18 are generally effective.
   • RS2 (Rim Chung's Special): This pattern can mimic both emergers and duns, making it versatile during the hatch.
3. Dun Stage Patterns:
   
   • Parachute PMD: This is a highly visible and effective dry fly that mimics the dun stage. It’s a staple in sizes 16-18.
   • Thorax PMD: With a low-riding profile, this fly is excellent for imitating the natural drift of PMD duns.
4. Spinner Stage Patterns:
   
   • Rusty Spinner: As PMDs transition to spinners, this pattern becomes incredibly effective. Sizes 16-18 are recommended.
   • Spent PMD Spinner: Mimicking the spent spinner with wings splayed out, this pattern is excellent during the evening spinner falls.

Tips for Fishing the PMD Hatch

1. Observation: Spend time watching the water to identify the stage of the hatch. Are trout rising to duns, or are they sipping emergers just below the surface? Remember in dry fly fishing rise forms are EVERYTHING!!
2. Match the Hatch: Switch your fly patterns based on what you observe. If fish are ignoring your dry flies, try an emerger or nymph pattern.
3. Presentation: Focus on a natural presentation. Use light tippets and aim for a drag-free drift to increase your chances of success.
4. Timing: Be patient. Sometimes the hatch might start slow and pick up as the day warms. Position yourself in areas where PMDs are likely to be abundant.

​The PMD hatch is a magical time on local trout streams, offering anglers the chance to catch numerous and often large trout. By understanding the lifecycle of the PMD and being prepared with the right fly patterns, you can greatly enhance your chances of success. So, the next time you head out during PMD season, bring along these tips and patterns, and enjoy the rewarding experience of fly fishing this prolific hatch.