fbpx Skip to main content
Fishing ForecastFishing Report

The Bugs of Autumn

By September 3, 2008April 14th, 2018No Comments


Fall is here. With the cool days will come the Fall Baetis, the Western Red Quill, the October Caddis and the Mahogany Dun. Hunting season has begun, as well as school, meaning most area rivers will have few anglers out and about. The fire near Silver Creek certainly scorched the bank on the south side of the conservancy, but had no affect on the fishing. By this time next year it will be hard to tell a fire ever happened here. With Fall in the air we thought it might be prudent to focus on the coming hatches this week, rather than the individual rivers.

Fall Baetis

This insect is normally associated with blanket hatches. The late morning, to early evening occurrence of this insect can bring every fish in the river to the surface. Look for these hatches on Silver Creek, the Big Wood, The Big Lost, and especially the South Fork of the Boise.

The Fall Baetis is a tiny insect and an active one. Expect to see this bug in size 22 to 20. A pale green to yellow body is accentuated by small opaque wings. The nature of this insect is to wiggle its abdomen briskly on the water, and on Silver Creek it is common for fish to key on this wiggle. The best way to imitate this is to fish your fly on a light, stout tippet – Flouro Carbon – is probably best for this technique. Use a lot of dry shake, and fish the fly on an open loop. This will free the fly up to pivot around and make it look more like the rest of the naturals. A variety of flies will imitate this insect with the Gulper Special being one of our favorites, although “Thorax” style patterns will pivot better on the waters surface. For Silver Creek, look at some of Rene Harrop’s patterns available in the fly shop

Red Quill

These bugs have already begun to hatch and signal a return to big insects on the Big Wood River. A Quill Gordon is an excellent choice to imitate this insect, although many left over Green Drake patterns from July will work as well. Essentially the Green Drake has a pale Green Body with Reddish bands where as the Quill had a Reddish body with Green bands. They are pretty much the same size and shape.

Expect to see this bug hatching and spinning in the middle of the day. Once the hatch gets really strong anglers will be able to use big attractors as searching patterns. Any of the Wulff flies are an excellent choice or the H and L Variant. Big fish will rise to these hatches, although it can be spotty. One run may have dozens of fish rising and a lot of insects, and only a mile away, there may be no sign of the bug. Stay on the move in the coming weeks to find this insect.

October Caddis

This is another large insect that we never see huge numbers of, but the fish love them and key on them none the less. A favorite fly for the October Caddis is the Royal Stimulator fished in the medium sizes. Large orange bodied Elk Hair Caddis and similar patterns will also work for this fly.

Expect to see occurrences of this fly on the Big Wood and the Big Lost. It is especially prevalent on the Big Wood north of Ketchum. Again, don’t expect to see hatches of this insect, but you will see their shucks scattered over exposed river boulders, much like we find the Stonefly shucks. It is an excellent fly to use for searching long stretches of river, and is also a good one to hang small Pheasant Tail droppers from while searching. The little size 18 Pheasant tails will imitate the emerging Fall Baetis well.

Mahogany Dun

The Mahogany Dun is a wonderful hatch that brings up the biggest fish on Silver Creek. It is also a notorious “Masking Hatch” that often occurs during the intense Fall Baetis hatches. Although a bigger insect than the Baetis (size 16) is often harder to see due to its color and the low light of autumn.

Expect to see this insect in the middle of the day and in good numbers. The hatches tend to start and stop for minutes at a time, so patience is a key to fishing when these insects are active. When they are going, the fish turn crazy for them. All the delicate presentations and caution one used more and more of with each passing day this summer, kind of goes out the window, as the fish become forgiving and very willing to grab a decent imitation fished on less then perfect drifts!

When fishing the Fall Baetis hatches on Silver Creek, be ready to make a quick switch to the Mahogany Dun and back again to Baetis when necessary.