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Tips for Fishing an Ant Fall

Tips for Fishing an Ant Fall

What are the most valuable bugs in your dry-fly boxthe ones that get you the most business, in the most places, for the longest period of time? Green Drakes? Salmonflies? Caddis? Hoppers? These are all big-time players, depending on where you fish, but there's another player that's often overlooked, but which should be included, and that's the lowly ant.

Think about it; ants are everywhere, they're around all summer and fall, and if you haven't heard the news, trout love them. After poking around with ant patterns in a number of places for a couple of decades, I've concluded that there are three situations in which it makes most sense to fish them: prospecting, unmatching the hatch, and during an ant fall.

Prospecting with Ant Flies

Starting anytime after runoff has subsided, and you can truthfully describe the season as summer, trout begin to eat terrestrial insects that end up on the water thanks to wind, bad luck, or I suppose, plain clumsiness. The terrestrials most fly fishers think of first are grasshoppers, mainly because they are large, and imitations of them are easy to see on the water. 

Photo by Paul Weamer

But ants are available to trout at least as often as hoppers, and it's possible that trout eat many more ants than hoppers through the course of a typical summer. We might miss them because they're hard to see on the water from our point of view, but the trout don't miss them.

Anytime you're prospecting with a dry fly you're looking for fish that aren't feeding on the surface right now, but have eaten enough bugs up there recently to recognize and appreciate another edible item coming down the feeding lane. Through the summer and fall an ant pattern is never a bad choice in a prospecting situation.

Use ant patterns to search along the shorelines of big rivers, and throughout the channel in smaller streams. Pay particular attention to grassy banks and areas of deadfall where ants are plentiful. The best "ant water" is less than 2 feet deep, moves at moderate speed, and has some cover on the bottom or on the bank. As with any dry-fly fishing, approach the water from an angle that keeps you out of the fish's sight, and be vigilant about achieving a drag-free drift of the fly.

Unmatching a Hatch

Another good time to try an ant pattern is when you're having trouble hooking a fish that's actively feeding on other insects. If you find a fish pigging out on a heavy hatch of small mayflies, like Tricos or Blue-winged Olives, things can get dicey. Dozens of naturals pass over the fish every few seconds, and your fly simply gets lost. Simple mathematics tells us it's unlikely that the fish will choose your fly over a real one. In these situations, it often helps to show the fish something slightly different, yet something it's still familiar with. After you've tried several logical imitations of the naturalsbut before you give up and lob a rock at the fish—try a small red, black, or brown ant.

Fishing an Ant Fall

Many fly fishers have experienced the fabulous dry-fly fishing that occurs when large numbers of winged or flying ants suddenly appear on the surface of the water. It seems odd, but the answers to some basic questions about this event are hard to find. Questions like: What is a flying ant? Are flying ants and crawling ants the same critter? Do all ants develop wings at some point in their lives? Why do a whole whack of flying ants end up on the water occasionally? And maybe the most important question to fly fishers: Is there a way of predicting when this might happen?

The best answers I found came from Oregon fly-fishing entomologist, Rick Hafele. He explained that when the time is right, an ant colony produces a new group of ants specifically for the purpose of starting new colonies. "These are not workers that suddenly get wings, but new individuals that are produced just for mating and starting new colonies. They fly away from the nest to locate new colony sites," Hafele says.

In the course of these migrations, it's not unusual for large numbers of winged ants to end up on water, presumably because of wind direction and other factors. It's probably not accurate to describe ant falls as random events, but neither do they seem predictable. In my experience around the Rocky Mountain West, it seems they can occur anytime in late summer or autumn, but are most likely in September.

Photo by Jim McLennan


We may not know when flying ants are going to appear on the water, but when they do, the trout eat them with gusto. There has been much speculation on what it is trout like about ants, including suggestions that it's their acidic taste, but it's hard to know about that one.

One sure thing is that when an ant ends up on the water, it can't leave the water. I believe the trout gradually realize this and develop a preference for bugs that don't fly away just as they're about to eat them. This is probably why trout also like emergers, spent mayflies, and spent caddisflies. Sometimes, but not always, the "fall" is made up of ants of varying sizes and colorsusually red, brown, and black, about a quarter to a half inch long.

When the sizes and colors are mixed, it's a perfect situation, for imitation is simplified and it probably won't matter which size or color of ant pattern you use. A fall of flying ants seems to be a one-day event, and is not likely to happen again on the same water the next day.

It's possible to be in the midst of a fall of flying ants and not know it. On a beautiful autumn day last October I fished to trout that were feeding on a sparse but decent hatch of Pseudocloeonmayflies. I caught a few rainbows and decided to pump the stomach of one fish to confirm what it was eating. When I extracted the glorp from the pump I found some mayflies as expected, but for every one of them, there were four or five black flying ants.

I consider myself a careful observer when I'm on the water, but I hadn't noticed the ants. So if you're on trout water in the fall and find fish rising to "mystery bugs," suspect flying ants. Look closely at the water and carry a little insect seine so you can catch and identify what's drifting on the surface.

Visibility Problem

The steps to successful dry-fly fishing are: 1) Choose a logical imitation of the natural bug; 2) Put the imitation in front of a fish; and 3) Make the imitation behave like the natural. It's simple in principle, but the whole process collapses if you can't see your fly because you don't know if you've accomplished the final two steps or not. Has the fish seen the fly? Is the fly dragging? If you don't know the answers to these questions you don't know whether the problem is with the fly or with the drift. You don't know whether to change flies or not, nor whether to adjust your cast or change your casting position.

So to effectively fish an ant (or any other nearly invisible fly), you have to solve the visibility problem. You might choose to use a hi-vis fly like a Parachute Ant, which helps in some water and light conditions.

Parachute Ant Fly Recipe

Photo by Jim McLennan

  • Hook: #12-20 standard dry-fly.
  • Thread: Brown or black 6/0.
  • Abdomen: Fine black, brown, or cinnamon dry-fly dubbing.
  • Post: White poly yarn.
  • Hackle: Grizzly.
  • Thorax: Fine black, brown, or cinnamon dry-fly dubbing.

Another way is to team the ant with a more visible dry fly. You can attach the ant to a hopper pattern with an 8-inch dropper. The dropper must be short so the flies stay close together and drift in the same current, which reduces the likelihood of drag. In addition to providing improved visibility, the two-fly method gives the fish two choices on the menu, and while it doesn't seem to make sense, it's surprising how often a big trout will take a #16 ant drifting just a few inches from a #8 hopper.

If the water is slow, flat, and shallowthe kind of place where the splat of a hopper might spook the fishchoose a smaller but still visible fly to pair with the ant. A #14 Parachute Adams is often a good choice, but light and water conditions might change that.

If multiple fly setups aren't legal where you fish, or if you're simply more comfortable fishing a single fly, you need another way to solve the visibility problem. In this case put a small, brightly colored marker on the tippet close to the fly. I use strike indicator yarn, sold under the names Lightning Strike or Strike 2. This synthetic yarn is pretreated for buoyancy, and comes in several hi-vis colors, including fluorescent orange and chartreuse. 

Attach indicator yarn to the tippet a few inches from your ant pattern. The amount of yarn shown here is for illustrative purposes. When ant fishing, use the smallest amount of yarn you can see on the water. Photo by Ron Finger

To attach it to your tippet, tie a small slip-knot in the tippet, then insert a piece of the yarn into the loop of the slip-knot. Pull on the two ends of the tippet to tighten the knot and secure the yarn in the loop. This holds the yarn in place without weakening the tippet. (see illustration). The marker should be positioned within a foot of the fly. You're not making a strike indicator, you're making a "fly locator," whose job is simply to be visible, so trim the yarn short.

The correct size is the smallest size that's still visible at standard fishing distance. The marker rarely needs to be more than 3/8inch across. After you make the cast, you'll be able to find the marker easily, and then you can usually find the fly. Skeptics sometimes ask if a speck of yarn drifting near the fly deters fish from taking the fly. I don't believe it does if the marker is small and doesn't drag. Trout are accustomed to seeing all kinds of debris floating on the surface near the flies they eat.

Jim McLennan is the author of four books, including the book of essays Water Marks (Fusion Books, 2008) and the guidebook Trout Streams of Alberta (Johnson Gorman Publishing, 1996). He lives with his wife Lynda in Longview, Alberta, where they operate McLennan Fly Fishing (

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