Spruce Moths have become one of the premier super hatches in the last few years. The Spruce Moth is a terrestrial species with cyclical populations. They have been highly destructive in many heavily forested areas and patches of dead evergreens can be seen on the sides of mountains where spruce moth populations are heavy. Local writers have criticized anglers for “liking” spruce moths. It’s not that anglers like the moths so much as the fishing opportunities the moths provide. Moths fall on the water in mass and trout meet their arrival with all the enthusiasm you’d expect. They’re one of the most active insects on the water in the west and their fluttering and dancing across the water creates some memorable antics from the trout.Spruce moth fishing is best in the summer moths and can be present s early as July but get thicker into August. Before the big flights of adults are present, moth worms can be seen hanging from the trees. These worms are usually about a half inch long and sort of a puke olive to cream color. We’ve had some good reports from anglers fishing inch worm type patterns in the appropriate colors along the banks lined with infested trees. The real show doesn’t start until the adults are present. Often the moths will be preset for a day or two until the fish really get onto them. Early in the “hatch” the best fishing is when the bugs are thickest on the water. Trout will start to chase these bugs across the water with frenzy. It’s common to trout repeatedly jumping out of the water for the moths. As you can imagine, this makes a dead drift much less important than normally required for rising fish. Often a skittered fly will draw more attention than a dead drifted one be consequently be more effective. Once the moths head back to the trees their imitations can still be effective search patterns especially if the trout are still hungry. Sometimes moth hatches are so heavy the fish will become gorged and stop feeding while the moths are still on the water. It’s quite a sight to see mats of moths floating down a run unmolested that had hundreds of rising trout minutes before. If the fish are not eating the naturals fishing with moth imitations is probably futile. In fact you may want to head to a different stretch of the river where the fish may be more active. Water temperatures can also be a factor on the trout’s reaction to the moths. Even in the summer moths it’s not that uncommon for water temperatures to drop into the forties by morning. This is especially true in cold canyon waters like the Gallatin. Moths may be present for w while before warming water temperatures spur the fish into feeding. After a midday lull, moths will return to the river in the evening but usually not in the same numbers as the mornings, perhaps because the trout have eaten so many of them.
When spruce moth populations first exploded a few years ago most local anglers just fished a 12 or 14 Elk Hair Caddis. Most days that fly still works as well as any but there are a lot more choices in spruce moth patterns now. Many are variations on the classic Elk Hair in colors a bit closer to the moth. Some of our favorites are the Snowshoe Spruce Moth and Summer Spruce Moth. Dan Delekta’s Twisted Baby in tan has also proven itself to be an incredibly effective spruce moth imitation. The normal size range is #12 to #14 but later in the summer fish will often rise to your moth only to nip at it without actually eating it. When this happens going down to a #16 can often make a big difference.