Caddis Flies

Understanding Caddis Flies and How to Tie Them

Of the most common insect orders (mayflies, stoneflies, caddisflies) found in trout streams, caddisflies seem to be the most difficult to figure out.

Much has been written about caddisflies recently, but few fly fishers can recognize whether trout are feeding on emerging or egg-laying caddisflies and as a result they are confused about fly selection and strategies.

Caddisfly Emergences
Like mayflies, most caddisflies rise from the bottom of the stream and emerge in the surface film. Unlike the slower mayfly, however, once a caddisfly breaks out of its pupal husk in the surface film and becomes a winged adult, its movement from the stream to dry land is relatively fast. Mayflies generally float on the surface of the water, often for a considerable distance, while their wings dry and stiffen.

Because it is uncommon for caddis adults to stay long on the water, a pattern imitating the emerging pupa fished in or just under the surface film is preferred by the trout.

To confirm an emergence of caddisflies, watch the fish and how they feed. The splashy riseforms and aggressive feeding of trout are signs of caddis activity, but there are other indicators. Riseforms are a result of many factors: the type of water a fish is holding in, the size of the fishand the behavior of the insects being fed upon. Many species of caddisflies emerge from fast water, and, generally, the faster the water, the more energetic the riseform as the fish reacts to escaping insects.

However, even in a fast-water scenario, anglers can be fooled. Look closely, often trout will feed in a thin seam just off the fast water, eating pupae that have been caught there. In fact, observation is crucial whenever you are in the midst of a caddisfly emergence.

Typically, in the early stages of a caddis emergence, the riseforms of the trout are splashy and aggressive, even in slow water. These riseforms are often caused by smaller fish. As emergence becomes more intense, the fish frequently settle into a consistent, less frantic feeding rhythm. Look for porpoising fish: first the head of the trout will appear at the surface, followed by the back, then the tail. When fish are porpoising and there are few adult flies on the surface, the pupae most likely are concentrated in or just under the surface film. At these times, a pupa pattern, such as the LaFontaine Sparkle Emergent Pupa, is deadly when fished in the surface film.

To confirm whether the trout are actually feeding on caddis pupae, hold a fine mesh net, such as an aquarium net, in the surface film downstream of feeding fish for several minutes. Look for fresh caddis pupal husks. They will appear transparent, with a slight yellow-orange tint, and should provide clues to determining the size and shape of the emerging species.

The most effective way to fish pupal patterns during caddis emergences is to dead-drift them in the surface film, as you would fish a dry fly. Grease the leader and tippet to within six inches of the fly to help suspend it in the surface film. If the pupa pattern has a wing of deer hair (as the LaFontaine Sparkle Emergent Pupa does), I rub floatant paste on the wing. Pupal patterns float low in the surface film and are difficult to see. Therefore, watch where the fly lands on the water so that you’ll be able to follow its drift or anticipate its drift. Whenever you see a disturbance in the water near where you suspect your fly to be, set the hook.

If dead-drifting an emerger pattern doesn’t bring fish, present the pupa pattern in a sweep across the current in front of rising fish. This is a traditional wet-fly swing and the angler is upstream of the fish. Rub floatant on the leader and the fly to cause the fly to skitter across the surface during the swing. I learned this presentation from my good friend, Wayne Anderson, who guides on Wisconsin’s Wolf River. He uses a LaFontaine Sparkle Emergent Pupa both during hatches and during non-emergence periods on rivers with large caddis populations.

Caddis Egg-Laying Behavior
The egg-laying (ovipositing) behavior of caddisflies is often more confusing to fly fishers than emergence activity. That there are clouds of caddisflies in the air does not mean necessarily that there is an emergence underway. In fact, the presence of large numbers of adults swarming over the water may be a prelude to egg-laying. In this case, excellent fishing is in store for the prepared angler.

To be sure caddisflies are preparing to lay eggs, watch the airborne insects carefully. If the adults are flying away from the stream and toward the shore (and there are fish rising), they most likely are emerging. If the adults are moving toward the water or diving into the water, they’re laying eggs.

It’s fascinating to observe egg-laden adult females dive-bomb the surface of the water to release their egg sacs or dive through the meniscus to jettison their eggs to the bottom. They remind me of Ping-Pong balls bouncing on the surface. The females often dive several times before their egg sacs are released or before they are able to penetrate the surface.

To represent these egg-layers, I use either a floating fly such as the Delta-Wing Caddis (imitating a fly lying in the surface film) or an Egg-Laying Caddis Wet Fly, which sinks and mimics the dive of the adult female. The Delta-Wing Caddis is fished dead-drift with occasional twitches to represent the struggles of the natural. The Egg-Laying Caddis Wet Fly is cast upstream so that it sinks as it drifts downstream, then swings to the surface on a taut line below the angler representing a female that has pasted its eggs on the
stream bottom and is swimming to the surface.

Ovipositing adult flies that fall to the stream’s surface after egg-laying can be imitated with a Spent Partridge Caddis in sizes #16-#20. The Grannom species exhibits this behavior and is found in many Midwestern trout streams. Fish the Spent Partridge Caddis dead-drift with occasional twitches.

Caddis Fly Patterns: A-C

Caddis Flies: Letters D-F | Caddis Flies: Letters G-O | Caddis Flies: Letters P – Z