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Fly Fishing the Big Hole River—The Spruce Moth Hatch

August is a wonderful time to be fly fishing the Big Hole River in Southwest Montana.  Everyone who has been chasing the Salmon Fly Hatches from river to river are now gone.  Evenings are getting cold and day time highs are warm.  Most people think August is a hatchless month when fly fishing in Southwest Montana.

Besides the hoppers, and ants, the one terrestrial hatch I look forward to every year is the Spruce Moth hatch on the Big Hole River.  The moth lives inside Douglas Fir Trees and Lodge Pole Pine trees.  Once the forests have dried out from the summer heat and lack of moisture they fly from the trees they dwell in, and flock to the river for a dip and become a meal for trout.   This hatch has not always been around.
 
We have seen an increase in the Spruce Moth population in the last 10 years.  This hatch on the Big Hole River is in my mind the best and most consistent hatch of the year, low clear water, with fish looking up crushing spruce moths on the banks.  The spruce moth hatch does not occur on the entire Big Hole River.  It is concentrated in the section where we have the most pine trees.  From Jerry Creek fishing access to Maiden Rock Fishing Access is where you will find the Spruce Moth hatch.

Size #14 and #12 tan elk hair caddis are the best imitations for the Spruce Moth.  We tie them at the Sunrise Fly Shop with extra bushy elk hair.  The moth will flutter on the water, so in order to make your pattern look like the real Spruce Moth you need to splay out as much elk hair as you can on the pattern you are throwing.

You will only find the Spruce Moths on or near banks.  Rarely do the moths flutter in the middle of the river.   This hatch is one that every angler should fish when taking a Southwest Montana fly fishing vacation.  You will be amazed how many trout are looking up to eat when the moths are on the water.  The trout eat so many Spruce Moths that I have seen them gorged on the meal almost like a Salmon Fly Hatch.

Since this is a terrestrial hatch, you do not have to fish a nymphal stage.  This is a great alternative to fishing Tricos in August.  Slamming the water with a fluttering Spruce Moth pattern is a blast.  The time of year when the moths are hatching is typically the first of August till about the 15th of August.  The best time to be on the water for the hatch is from 9:00a.m. - 2:00p.m.  Usually you will see a slowdown of moths on the water in the heat of the day.  Around 6:00p.m. the moths will return to the water for another feeding frenzy.

This year the hatch is late just like all of our hatches on Southwest Montana fly fishing rivers like the Big Hole River and the Beaverhead River.  We’ve had dry warm weather for the last 2 weeks so the hatch is just starting to pick up.   We have had a few Spruce Moths on the water this week with some fish keying into them.  Look for the hatch to get going in the next 5 to 7 days and get ready for the best dry fly fishing of the year on the Big Hole River!  Click here to learn more about fly fishing the Big Hole River or to see the latest Big Hole River fishing conditions.