Midges (Diptera)

Midges are the most abundant insect in almost all of rivers and lakes important to fly anglers. The majority of midges are the tiniest insects (hook sizes #20-28) on the water and for this reason are often overlooked. What they lack in size they more than make up for in numbers. During intense hatches tens of thousands can hatch over a few hours and create periods of heavy feeding. When trout key in on these ‘crumbs’ they can be very selective, which can cause plenty of head scratching. Some insight on the life cycle of these minute bugs may help on the next winter outing to your local river.

Larva

Most of the life span of a midge is spent as a larva. In this worm-like stage of life, it is not very mobile and can be found at the bottom of slow deep pools and runs within the sediment. During winter months trout tend to hold in the same types of water. Without observing trout in an obvious feeding behavior there is a good chance that they are sitting on the bottom waiting for food to drift in close proximity. For the best chance for success in this situation is to have larva patterns drifting naturally at or near the bottom.

Pupa

When a larva matures it begins a transitional stage before it becomes a winged adult called a pupa. In this stage, the pupa begins to swim in short bursts to the surface. Between these short bursts the pupa rests and drifts naturally. During periods with large numbers of pupae, trout may hold in the portion of water column with the best chance of intercepting them. When observing feeding fish holding higher in the water column, drift a pupa and emerger patterns with little or no weight at the appropriate depth. If the water clarity makes it not difficult to see, this type of feeding can also be observed with the occasional ‘dimple’ or ‘ring’ made by a feeding fish near the surface. These ‘rings’ can often be mistaken for dry fly feeding and cause plenty of frustration to the unsuspecting angler.

Adult

For anglers that have not ventured out much in the winter months, it can be hard to imagine fishing with dry flies. Although it may be for very short windows, open rivers will produce surface action on most days. Observation of how the trout is feeding can be critical in choosing the proper fly pattern. With quick or more aggressive rising look for patterns that have hackle around the body or head to keep the fly resting just above the water. If you see slow to lazy feeding try using patterns that sit on or in the surface film. It is important to mention that matching the size can be extremely critical for success with this type of fishing. If fish continue to rise around your fly, tie on the next smaller size. Without knowing how long the dry fly action will last switching flies after one or two refusals in crucial.

These are just some general rules to keep in mind when out on the river during the winter months. Of course, once you gain experience you will find exceptions to these rules, but that is part of the adventure.