The Lifecycle Of Midges

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Non-biting midge flies, or chironomids, are a predominant fly seen on the North Platte River in March & April. Adult midges have clear or dun-colored wings that lay flat against their bodies when they are on the water surface. They are a long and thin insect with a segmented body and are typically black in color.

There are 4 life stages of a midge: Larva/Nymph, Pupa/Emerger, Adult/Dry, and Spinner, and all within a one-month span. Clusters of midges indicate mating and the females lay their eggs on the surface of the water or on the surface of aquatic vegetation. The eggs sink to the bottom, and within about a week, they start to hatch into their Larva stage. Although midges can begin to hatch in water temperatures as low as 33°F, the peak of the hatch starts around 42°F.

The Larvae will burrow into the mud or hide under rocks and consume all kinds of organic matter while they develop into their Pupa stage, which can take 2-7 weeks, depending on the water temperature and condition. You can find the Larvae on the underside of rocks during this stage. They’ll typically be dark red due to the hemoglobin in their blood, allowing them to survive with low oxygen levels. When they are close to their Pupa/Emerger stage, their color changes from dark red to black. They are usually no bigger than a grain of uncooked rice and resemble a small worm (think of a Zebra midge).

The Pupa/Emerger stage only lasts 2 to 3 days, before the midges start emerging to the surface and become full adult midges. During the Emerger stage, they have a small air pocket to help them breathe as they come up to the surface. Once the adults emerge, they immediately leave the water surface, swarm together and start the cycle over, clustering with hundreds or thousands of other midges to create new midges. The adult midges do not feed, as their only function is to reproduce.


There are dozens of different midge patterns on the market and each of them is very effective at hooking trout. Below are some of my favorite nymph & dry-fly patterns. I would suggest using light tippet, 4x or 5x, especially when dry-flying.

Nymph patterns Zebra midge (size 18-22) Juju midge (size 18-22) Mayhem midge (size 18-22)

Dry fly patterns Griffiths gnat (size 18-22) Sprout/sipper/parachute midge (size 18-22)

Air and water temperatures in March and April are generally still chilly so the fish will most likely be in the slower and deeper water. For nymphing, try shelves with drop-offs and on seam and current lines. As the temperatures start to rise through April, the fish will begin moving into the thinner and quicker riffles to create their Redds (spawning beds). You’ll often see fish chasing each other across these white and gravelly areas, competing for the ability to fertilize the eggs on the Redds. After the fish have finished their spawn, they will temporarily move back into the slower water to recover, then shift back to the quicker water just in time for the baetis hatch.

Dry fly fishing in March and April can be a very fun and effective way to fish. Fish on days with low wind and overcast skies or find yourself a sheltered bank line, and you’ll more than likely find rising fish. There is also the “magic hour”, which is the final 30 to 60 minutes of daylight. There will be lots of midge clusters on the surface of the water and fish will continuously rise to feed on these clusters. Be aware of where the Redds are and only throw to rising fish. Many of the fish can be found in the “flats”, the slower and flatter water without much in the way of riffles or disturbances.

Article written by: John Zawacki

The Lifecycle Of Midges was last modified: February 26th, 2018 by Luke Keil

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