tactics

Craneflies

By Jeff Morgan

Craneflies are generally overlooked by anglers, but they can be important both in their larval and adult forms.

Images

(See the entomology page for photos)

raneflies are commonly called "Daddy-Long Legs," "Mosquito Eaters," or "Mosquito Killers." Entomologists call them the family Tipulidae. Most fly anglers don't call them anything, believing they are irrelevant to their fishing. Too bad, because trout often call them "lunch."

There are only a few species of truly aquatic craneflies, but even the terrestrial larvae are fond of moist soil near streams. The damp, loamy floor of the Western Cascade rainforests is perfect habitat for craneflies. Many of the riparian zones in those regions teem with the larvae, which are unleashed to waiting trout by the runoff of a rainstorm.

The Northwest is not the only place craneflies call home. Some species have adapted to the harsher conditions of the Great Basin and Rocky Mountains. In fact, anywhere you fish for trout you can be pretty sure that there are cranefly larvae in, under, or very near the water.

Common Western Species

Tipula, the cranefly genus, has a number of semi-aquatic species, which are obviously the most important to anglers. This is an extremely diverse genus, with over 70 species in California alone. However, they rarely occur in densities that motivate trout to feed selectively on them, so a simple approximation of color and size is all that is necessary for fly fishers.

Common Species of Tipulids include:

1. Tipula furca. Extends from the Rocky Mountains east to the Atlantic, and is very cosmopolitan in its habitat choices. The larva is olive-brown in color, and ranges from 5/8" to 1 1/8" in length when mature. The adult is brown to tan and about the same length, though with all those gangly legs and wings, it is difficult to give an official "length"!
2. Tipula augustinpennis. Common in the colder waters of the West, and I have seen good populations of this insect around the Crooked and Deschutes rivers in Oregon. The adult is a pale yellow or tan, and is about 1/2" to 1" in length. This insect is the prototype for many of the "cranefly" imitations that circulate in the Northwest. It is important to remember that this is an unusually small tipulid, and larger imitations are necessary to imitate most craneflies.
3. Tipula abdominali. Schwiebert calls it "perhaps the largest Tipulidae in our streams," and he is right on. This is the big dog of craneflies in the West. Natural larvae average one to two inches in length, and can reach upwards of three inches! These insects are often a drab olive to a greenish-gray in color. The adults are quite large, and brown or gray. This large tipulid is even more prone to nighttime activity than other craneflies.

Larvae

Most people will recognize an adult cranefly: fairly skinny body, very long and frail legs, and long wings which usually lie over the back. However, the larvae of these insects are probably foreign to anyone who has not actively pursued them.

Larvae resemble thick worms, with a usually cylindrical, occasionally flattened, body that is somewhat blunt at the head and slightly tapered at the rear. Colors are often drab, with grays, light olives, and light tans being most common in the West. They are easily distinguished from other large aquatic grubs because of their retracted head.

Most cranefly larvae are terrestrial, making their home in the soil near, but not under, streams. There are some aquatic tipulids, and these larvae are most common in mossy bottoms or in areas where the riparian soil is often too dry or rocky to allow good burrowing (like in the Great Basin).

Many of these insects are herbivores, though some are aggressive predators that actively seek out midge and mosquito larvae. However, the feeding habits of most genera are subterranean. This means that they become available to trout only when flooded-out by a spate, not because of particular feeding habits.

When they are washed into a stream, they are very much sought after by trout. The larvae have no swimming ability whatsoever, and once they are caught up in the drift, they are goners. With these larvae commonly reaching one to two inches in length--and some species pushing three inches--you can be sure that trout rarely ignore such a large morsel.

Imitating the larvae is a simple endeavor that is much more dependent on when you fish, rather than how. Spate flooding can cause many to be washed into the flow. Most anglers avoid streams in the day or two after a heavy rain, preferring to tie flies or count their stock options, but I can usually be found on a roily Oregon creek, lobbing larva imitations under a big indicator.

The days following a rain are prime-time, maybe the only time, where fishing cranefly larvae can be very productive. The only other time I have done well fishing cranefly larvae was downstream of about 30 anglers at Buffalo Ford, on the Yellowstone River. The larvae that lived in the mosses that coat the bottom were dislodged by the incessant wading, and the trout downstream were enjoying some fat grubs for lunch, until they ate my fraud.

It is best to dead-drift larva imitations near the bottom, for the naturals have no swimming ability. Also, keep your imitations near shore, where the larvae originated; fish in this area are more conditioned to seeing the naturals. Of course, fishing cranefly imitations on small streams, where the shoreline is always nearby, is much better than on large streams.

Flies for the larvae are very simple, because the shape of these insects is more or less that of a worm or grub. Since many of the larvae are translucent, a thin dubbed body of pale-olive, gray-olive, or dark gray dubbing, brushed out and clipped short, with a head of black ostrich herl, can be a deadly pattern. Another good pattern is a simple body made by wrapping a cut of Body Stretch (or any synthetic plastic sheet) up the length of a hook. The result is a segmented body, tapered at the head and tail--a very good imitation of the natural. Adding a dubbed underbody to this pattern will make it thicker, which sometimes can be important.

You should weight all larva imitations, because they need to be on the bottom; the extra bulk seems to only improve the success of the pattern. Don't be afraid to get big with these nymphs, I have tied imitations on size 4 4X long streamer hooks and still hooked trout. However, the best sizes are between size 12 and size 6.

Pupae and Emergence

The pupa stage is largely unimportant to anglers. Almost all cranefly larvae, terrestrial and aquatic, migrate to stable ground near streams to pupate. They pupate under the soil (or leaves and logs, if the soil is unsuitable), for one to two months. Because cranefly emergence is spread throughout the spring, summer, and early fall, and since pupation is done on land, the exact emergence period is of no significance to anglers.

Adults of both aquatic and terrestrial craneflies start to emerge during April in the lower elevations and late May in higher elevations. They continue to emerge throughout the summertime. Adult numbers wane slightly in the mid-summer, but increase as September rolls around.

Adults

Adult craneflies are clumsy fliers, so they are sporadically available to trout. Adults prefer the shady and cool riparian zone during the summer, and can be found hanging around ferns and the rootwads of fallen trees, as well as streamside rocks and brush. The best indicator that you have in perfect adult cranefly habitat is when you walk into a stream corridor that is 20 degrees cooler than outside the corridor.

Perhaps the reason we don't see many imitations of cranefly larvae or adults in our local fly shops is that they are overshadowed on many of our "glamour" streams. Rivers like the Deschutes, Yellowstone, and Henry's Fork have moderate populations of Tipulids, but they also have many other insects that draw our attention away. But the value of craneflies to a lover of the smaller stream cannot be disputed. As with terrestrial insects, the smaller the stream, the greater the shoreline-to-surface ratio, so there is a greater likelihood of a cranefly entering the streamflow. They are a food source that is quickly recognized by the trout, and are just as quickly pounced upon.

Most adult "imitations" you see in America are rather amateurish. Spider patterns or things that look like big midge patterns are all I was able to find when flipping through American fishing literature about five years ago when I started concentrating on craneflies.

To look for good imitations, you need to open a book or magazine on English flyfishing. They made fishing "the daddy" an art, and really have some amazing patterns.

My favorite was adapted from a pattern tied by Davey Wotton. The body is extended deer hair, the legs are knotted pheasant tail, the wings are pre-cut Spirit River Caddis wings, and the hackle is grizzly or brown. The resulting pattern is very light, quick-to-dry (often never needing fly floatant), very visible, and a near-exact imitation of the natural. Because of this pattern's bulk, you rarely hook fish under seven inches in length, which is a blessing on a small stream.

Adult imitations are particularly effective in two locations: small streams with dense overhead canopies that provide near-constant shade, and meadow streams. In both these locations, adult activity is at its maximum on calm, warm evenings. I rarely pull out adult cranefly patterns in the heat of the day, preferring to wait until the shadows hit the water.

When fishing adult imitations keep them near shore, where fish are likely to have encountered the natural before. It can be effective to skate these patterns by greasing them with floatant and skittering them across the surface. Despite the aggressive strikes this technique can produce, it is rarely more effective, day-in-day-out, than a simple dead-drift.

Jeff Morgan has written many articles for Westfly, mostly on entomology and fly tying. He is the author of An Angler's Guide to the Oregon Cascades and Small Stream Fly Fishing. Jeff is currently a graduate student at Stanford University, where he is finishing his PhD in History.

Uploaded 08/25/2000.

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