How to Pick the Right Fly (Part 4): Midges 101

This is the fourth article in our series on how to pick the right fly for any fishing situation. To see all the posts in this series, click here. 

By Spencer Durrant

According to renowned guide Pat Dorsey, midges make up as much as 50% of a trout’s diet in certain watersheds – not unlike the percentage of my diet that’s made up of potato chips…

Kidding aside, midges really are that abundant. They’re stacked in racks at every trout gas station and grocery store on the planet, in just about any flavor you can imagine.

Dorsey has guided on Colorado’s South Platte River for decades now, and he’s an authority on midges. In an article for  Fly Fisherman Magazine, he says that anglers who are intimidated by fishing midges are often worried about using “spiderweb tippets and minuscule flies.”

That’s a fair concern, but not all midge fishing has to be done with tiny patterns. As with any other aquatic insect, you’ll be successful at fishing midges once you understand and recognize their life cycle.

This post will simplify some of the knowledge about midges, and give you the actionable info you need to hit the water and catch fish with these flies.

What is a midge?

Midges are small flies, related to the mosquito. Thankfully, midges don’t bite!

Midge has become a bit of a catch-all term for any small fly, so it’s important to note here: midges are a distinct species of aquatic insect. Midges are small, yes, but not every small fly is a midge. Midges are a distinct insect, just like caddisflies, mayflies, and stoneflies.

And as with caddisflies and mayflies, there are a ton of different types of midges. Like those bugs, though, you only need to understand the following before you’re ready to fish with midges:

• Midge life cycle
• What a midge looks like
• Best patterns to imitate midges

Even though midges are tiny bugs, they’re not all that tough to fish. Even midge dry flies are simple, and understanding these bugs gives you a tool you can use year-round. Just this past winter I caught a 22-inch cutthroat on a midge dry fly. So, don’t let the size of a midge prevent you from fishing one.

Now – let’s move on to the need-to-know info about midges.

Midge Life Cycle

The midge life cycle is similar to that of mayflies. A midge starts life as a larvae, when it looks like a short, curved worm with a segmented body. If you overturn rocks to look for bugs in a trout river, you’ll almost certainly find a few midges wiggling around.

The next stage is the pupal stage, when a midge gets ready to emerge as an adult. A midge pupa is shorter, fatter, and more heavily segmented than the larvae.

Finally, a midge becomes an adult, which is characterized by a slim body, small head, small legs, and short, flat wings tucked against its side. This is when midges look similar to mosquitoes.

Midges hatch year-round, even during winter. Their abundance makes them a constant food source for trout in virtually every river.

Identifying Hatch Stages

Midge hatches move along similarly to mayfly hatches. Larval midges cruise around the river bottom, where they’re easy prey for trout. Once a midge becomes a pupae, its behavior changes. According to Pat Dorsey, pupal midges become “fidgety” before emerging into adults. Instead of shooting straight toward the surface like mayflies or caddisflies, midge pupae move up and down several times throughout the water column before emerging as an adult. Dorsey notes that a midge emergence is a slower process, which makes them an easy target for hungry fish.

An adult midge behaves much like other adult aquatic insects. Trout key in on crippled adults, or adults stuck in the surface film, throughout a hatch.

So, knowing what the hatch stages are, how do you know when trout are eating emergers versus adults?

By studying the rise forms trout create when eating bugs off, or near, the surface.

Think of rise forms like old-school text messages. Rise forms are brief communiques that, at first glance, don’t make sense. With a practiced eye, though, you can decode a rise form as quickly as we all understand “l8r.”

Emerger Rises

Trout eating emergers create a unique rise form. Instead of seeing a fish’s head when it eats, you only see the back and tail fin. This happens because fish are eating bugs as they travel to the surface or are stuck in the surface film – emergers and cripples. In the case of midges, we can include pupae, too.

So – if you know midges are hatching but only see a trout’s back when it rises, chances are it’s eating an emerger, cripple, or midge pupae.

Dun Rises

When trout eat duns, they create the classic dry fly rise form. Their head breaks the surface, leaving behind the “ring of the rise” we’re so familiar with.

Since midges are so small, trout will eat clumps of them in a single rise (if the bugs are floating in clumps, of course).

Matching the Midge Hatch

Matching the midge hatch is like pairing the right chips with your sandwich – do you go for the classic plain potato chips, or opt for something spicy to give your meal a kick? The choices are just about endless.

That’s how it can feel when you’re picking a fly to match a midge hatch. With so many options, where do you even start?

Start by looking at the real midges on, or in, the water. Then, you want to pick a fly based on these characteristics:

• Size: This is the most important factor when choosing a fly. Your fly needs to be the same size as all the real bugs you see in or on the water.
• Shape: Midges all share generally the same shape, but this is still important when picking a fly.
• Color: Color is the least important characteristic to match with your fly. Some fish on heavily pressured waters might get picky about color, but most don’t.

Midges are generally between size 16 and 26. Most of my go-to midge patterns are a size 20. You’ll scale up and down based on the hatch, but if your collection of midge flies is between 16 and 26, you’ll have something that’s the right size for just about any midge hatch.

As far as shape and color are concerned – make sure you have a wide variety here, too. The more flies you have in your box, the more chances you have to perfectly match whatever’s hatching.

So, here are a few of my go-to midge patterns, and where they fit within each stage of the hatch:

Midge Larvae

• Zebra Midge – a time-tested, classic fly that works everywhere
• WD40 – perfect for adding variety to your midge larvae patterns

Midge Pupae

• Shop Vac – a fun pattern for midges that are close to emerging
• Rainbow Warrior – not really a midge pattern, but works well in some instances

Midge Adults

• Griffiths Gnat – perfect for imitating a cluster of midges
• Parachute Adams – this fly really can imitate just about any bug!

Go Fishing

The great thing about midges is that they hatch year-round. Even in the dead of winter, you’ll find fish snacking on these flies. Some of my best fishing days each year are during January midge hatches. I look forward to fishing a midge hatch almost as much as some anglers anticipate a good BWO hatch.

Take this knowledge, study it a bit, add some variety to your fly box, and go put the information we covered today to good use. Let us know if you catch anything on a midge!

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