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Missoula’s Skwala Hatch: When it all Comes Together - Skwala Fishing

Missoula’s Skwala Hatch: When it all Comes Together

By Aidan Morton 



On a warm, overcast afternoon in April, Missoula, MT, is home to some of the most spectacular fly fishing in the West. Small mayflies, midges, and the famed skwala – a large, gawky stonefly– dip and hover above the water’s surface. Rain, snow or shine, these bugs kick off their annual big hatch in early spring, laying the groundwork for some of the earliest and most chaotic dry fly fishing of the year. This is your best chance to dance with a two-foot trout crushing dry flies.


Skwalas live for years clinging to stones and wood on the river bed before crawling to the shore to emerge as adults. What ensues is a miraculous display of fluttering stoneflies crawling or diving into the riverbank. Shortly after, they return to the river’s surface to lay their eggs–– and trout take notice in a big way.

A handful of skwala nymphs.
 A handful of skwala nymphs. 

A big trout is a clumsy skwala’s worst nightmare. All three of Missoula’s major rivers see this hatch, however the Bitterroot and Clark Fork Rivers are graced with the highest numbers of skwalas. Mature, cunning trout move into shallower, tricky feeding spots to pick off as many skwalas as possible while these insects make their trips to and from the riverbank. Eager trout gorge themselves on adult skwalas because they are easy and plentiful in Missoula’s rivers like nowhere else. Naturally, anglers shed their winter blues and ring in the spring season with the first sight of these bugs. Our friends at Grizzly Hackle Fly Shop in Missoula catch some of their biggest fish this time of year. For those fly fishing in western Montana, the skwala hatch is like a holiday season.


We first see signs that the skwala hatch is upon us in late March, as the days get longer and the final marks of winter begin to recede. The skwala hatch happens in a tight window that precedes runoff in the Missoula area. We see some of our coldest days of the year into late February, and come May the volume of Missoula’s rivers violently increase tenfold. For roughly six weeks in March and April, excellent dry fly fishing opportunities emerge among dynamic conditions. Spring in Missoula is one of the only times and places where you can have excellent dry fly fishing on bluebird days and in blizzards alike. Skwalas are the highest source of protein for hungry trout after their long winter interlude, and big rewards can be found by those brave enough to weather the conditions.


Anglers can approach the skwala hatch in various ways. In early spring, our rivers’ flows bump up just enough to create and flood new side channels and sloughs. These areas provide excellent opportunities for curious anglers to hunt big fish in small water. Additionally, excellent skwala fishing can be had from a driftboat or raft. Grizzly Hackle guides prefer to fish this way, where anglers have the ideal position to tuck tight casts anywhere on the river. Carefully placing a big foam stonefly in “big fish water” is the key to getting blown up this time of year. Water temperatures are still low prior to runoff, and depending on the day-to-day conditions fish can be holding in different areas. Big fish will often hold in slow tail-outs or under debris in outside bends to avoid expelling unnecessary energy when their caloric intake is still low. As the skwala hatch progresses and temperatures rise, fish can be found eating skwalas in faster water such as riffles and quick seams.


Adapting to dynamic conditions is critical when fishing the skwala hatch. Trout are typically “dumber” as they begin to key in on these adults, and slowly become more selective as the hatch progresses. Many anglers anticipate clouds when fishing the skwala hatch, but clarity and weather conditions are significantly less important to a good day of fishing when compared to the summer months. Instead, a diverse selection of flies and gear is vastly more important.


 An adult skwala dries its wings
 An adult skwala dries its wings. 

Anymore, it’s no secret that Missoula is home to some of the earliest dry fly fishing of this kind anywhere in the country. In result, trout become wary of flies and presentation as the hatch goes on. Having various skwala patterns ranging from sz. 10-14 increases your chances of catching fish no matter the conditions. For the most part, we look for flies that land in the sweet spot of optimal buoyancy with a low-profile. Female stoneflies are easily distinguishable because they are larger, in the sz. 10-12 region, and carry a large black eggsack on the end of their abdomens. Males, on the other hand, typically size in the 12-14 range. While poor fliers regardless, only female skwalas have the capability to fly. Keeping these distinguishing characteristics in mind can help you prepare your fly box before a trip and even give you options when trying to convince a big fish to eat on top while on the river. Several of our favorite flies include the Plan B, Rogue Stone, Rastaman Stone, Dancin Ricky, and Water Walker. Nymphing Pat’s Rubberlegs, Double-bead Stones, Twenty Inchers, Copper Johns and San Juan Worms are also great choices when fishing earlier in the day or when the dry fly action just isn’t happening. We fish 5 and 6wt. rods this time of year and use 7.5 ft or 9ft. leaders that taper down to either 3 or 4x. No need to get finicky with tippet size, as a thicker diameter is necessary to larger double-dry or dry-dropper rigs. It also comes in handy when fighting that fish of a lifetime. It’s hard to imagine a time where the skwala hatch was the best kept secret in the Missoula and the neighboring valleys, but the fishing remains remarkable.

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