The Spruce Moth

Spruce moths originate from coniferous forests, particularly those impacted by spruce budworm infestations. When they fall into rivers and streams, these insects inadvertently become a significant food source for trout.

The spruce moth’s lifecycle begins as larvae feeding on spruce and fir trees. By mid to late summer, the adult moths emerge and become active. Wind or natural clumsiness often deposits these insects onto water surfaces. Trout quickly key into their presence on the water, creating a few weeks of exceptional dry fly fishing on many of Montana's storied fly fishing rivers.

The Top 3 Montana Rivers for the Spruce Moth Hatch

1. Gallatin River

Focus on the canyon stretch between the Yellowstone National Pak boundary and Gallatin Gateway, where the many overhanging trees provide ample opportunities for moths to land on the water. The fast current and pocket water character of the Gallatin River trap fallen moths in the river, making them an easy meal for waiting rainbow and brown trout.

2. Blackfoot River

Famous for its connection to “A River Runs Through It,” the Blackfoot River is legendary for its dry fly fishing during the spruce moth hatch. The river corridor between Bonner and Ovando is lined with overhanging conifers that are alive with spruce moth activity during July and August.

3. Big Hole

The river stretches upstream of Wise River flow through a patchwork of agricultural fields and conifer forests. As the Big Hole River meanders down the valley, it pushes up against forested hillsides teaming with spruce moths. Winds and errant flights ensure that many of these terrestrial insects find their way to the river’s surface where they quickly become a preferred meal for feeding trout.

Top 5 Spruce Moth Flies for Fly Fishing in Montana

1. Fathead Moth (Size 14) - Specifically designed to imitate the adult moth, the spun hair head and wings keep this fly highly buoyant in the fast water associated with upper river drainages.

2. Tan Elk Hair Caddis (Size 14-16) - A versatile dry fly that works well as a spruce moth imitation. Its buoyancy and natural appearance make it a Bozeman fly fishing guide favorite.

3. Parachute Spruce Moth (Size 14) - With a parachute-style hackle for visibility, this fly is ideal for anglers targeting tricky feeding lanes on the upper Madison or Gallatin during the hatch.

4. Tan Chubby Chernobyl (Size 14 - 16) – This high-floating dry fly checks the boxes for visibility and floatation. A terrific pattern for prospecting over likely holding water with a dry/dropper setup.

5. Hare’s Ear Trude (Size 14) – The calf hair wing and light body color give this pattern a nice blend of realism and function. This is a great pattern when fishing gentle glides and soft seams on mellow river stretches like Paradise Valley on the Yellowstone River.

Angling Tips for the Spruce Moth Hatch

Best Time of Year - The spruce moth hatch occurs during the summer months between July and September. Typically, trout quickly key into their presence once they become active in neighboring forests. Although the moths are around and active for several weeks, the best action is within the first few weeks of their arrival.

Presentation Technique – Trout feed opportunistically on spruce moths and will move several feet to quickly take a natural within seconds of it falling into the water. Blind casting over likely holding water with high floating dry flies enables the angler to quickly cover prime water for aggressive trout.

Rod and Fly Line Recommendation - Clear water and sunny skies are standard when fly fishing in Montana during the prime midsummer season. Fast action fly rods like the St. Croix Evos, Scott Centric, or Sage R8 Core paired with an Elite Rio Gold fly line are excellent setups for summertime versatility.

Best Time of Day - Early morning through early afternoon often provides the most consistent action. Moths become increasingly active in the mornings as air temperatures rise. Windy days can be great for fishing when spruce moth activity is at its peak.

Experience Montana Fly Fishing with Fins and Feathers

Summer hatches quickly wane by late July when the trout of Montana’s rivers turn their attention to terrestrial insects like moths, hoppers, and ants. Spruce moths are an important food source for trout during this time, trout quickly respond to their presence. Montana fishing guides know to switch to spruce moth imitations when they see them flying near the water.

Fins and Feathers Guide Service has been outfitting Montana fly fishing trips for over two decades. July and August are two of our favorite months of the year for dry fly fishing opportunities on the rivers near Bozeman. Although aquatic insect hatches here are sparse this time of the year, trout rise regularly to a variety of terrestrial insects such as spruce moths.

Contact us to learn more about our guided fly fishing trips near Bozeman or across Montana during the summer months. Reservations can be placed online, via e-mail, or by calling us at 1-406-468-5019.