The Midge Life Cycle
Here in South West Montana, we have a lot of hatches. You hear anglers talk about the "Famed" Salmonfly hatch in late June, PMD's throughout July, and the Caddis mania in Summer afternoons. These insects are great and truly make trout fishing what it is, but it can take away hype from some of the less common aquatic food sources available in our local waters. Non- biting Midges are the most prominent insect that can be found throughout the year, especially in Winter. These tiny relatives of the common Mosquito can hatch in thick numbers, enough so to gain the attention of a trout as a source of reliable food, making them a must-know for those who seek a better understanding of their surroundings.
This is the second of four-stages, the first being the egg, in Midge's life-cycle and is the most common imitation to fish. These "worm" like larva are small and simple for anglers to imitate when on the water. Their color varies due to their diet but some of the most common include black, red, and olive variations. These are fished subsurface throughout the year but most popular throughout the Winter months due to the lack of other food sources available to fish.
The Pupa is the third stage of the life-cycle. The key difference between the larva and the pupal stage is the curvature in the Midge's body and the air bubble that forms when their wingcase begins to grow. This stage is the most vulnerable during their life. This allows trout to key in and easily target the tiny insects and can provide some excellent angling opportunities. This stage occurs with large numbers of midges pupating and can create an absolute feeding frenzy. There are many patterns that imitate this stage but a lot of the standard nymph patterns can be considered an emerger/pupal stage because the bead or flash tied in to look like the bubble that forms.
This is the final stage in a Midge's life and they can finally begin their mating sequence to continue the cycle. This, for a lot of anglers, is the most fun to fish. This provides dry-fly opportunities when nothing else is on the surface of the water and is the "fix" until Spring. Midge adults are very tiny and dance on the surface or slightly above the surface. This stage wouldn't be nearly as entertaining for trout if they weren't in great numbers. Often during a midge hatch, you will see the adults cling to each other in clusters, and in great numbers, they begin to appeal to fish as a food source, causing them to rise. This is the best time to fish dries for trout during the Winter. These patterns are difficult to see and often anglers will fish these flies trailing a larger dry that acts as a sighter for when a trout eats.