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article by Ron Newman

Scientific Name:

  • Class - Insecta. Order - Hemiptera. Family - Corixidae (over 100 species)

Common Names:

  • Waterboatman, Boatman, Water Bug, Water Beetle, Paddle Bugs


  • This is the only non-biting or non-stinging member of the water bugs. It should not be confused with the larger Backswimmer (family - Notonectidae). Since it doesn't bite like the Backswimmer, the boatman is a preferred food source of trout in our interior lakes. If you have ever been stung by a Backswimmer you will understand why the trout tend to avoid them. Also note that the boatman is a water 'bug' and not a beetle (Order Coleoptera).

Life Cycle:

  • Waterboatmen spend most of their life in the water but do not have gills. When a tiny boatman nymph hatches from the egg it will swim to the water surface to get its first breath of air. It will also grab an air bubble with its modified legs and then swim back down to the lake bottom. Throughout its life, the boatman nymph will make many trips to the surface to replenish this air bubble for that is how it breathes. However, this bubble does act somewhat like a gill in that it absorbs oxygen from the water allowing the boatman nymph to stay submerged for long periods of time. Over the course of the summer the nymph will feed on aquatic vegetation, algae and a few aquatic larva of other species and gradually mature into an adult. When the timing is right, the adult will swim to the surface, hesitate while the wings dry and then take flight. It will join a few, or many thousands of other Waterboatmen in a mating flight. The adults will mate in flight and then re-enter their aquatic home where the fertilized female lays her eggs on the submerged stems of aquatic vegetation.


  • The boatman is characterized by two 'paddle' like appendages that are used for swimming (or paddling) through the water. These paddles are one set, of three pair of legs and are the farthest from the head. The widened paddle like appearance is from the 'swimming hair' on the ends of this set of legs. The other legs of the boatman also have hair, which is used to hold the air bubble for breathing. While clasping this air, the 'paddles' are the only easily apparent legs since the others are held close to the body with the bubble. These bugs have large compound eyes and the head almost appears to be a part of the elliptical shaped body.


  • In the fall boatmen get up to about 1/3 inch in length (large females can reach inch) and are generally smaller (about 1/5 inch) in the spring. When extended the paddles are about as long as the bug.


  • The upper winged surface of the adult is actually a rich, dark brown with black mottling that will appear as almost black at a casual glance. The underdeveloped wings of the immature are black. The underside of a boatman is generally a white to yellowish color but may also be a pale green. The air bubble that the boatman carries underwater next to its underside will often give a silvery appearance to the abdomen.


  • The boatman is only semi-aquatic. Adults will leave the water and fly. When returning to the water the boatmen will often splash down, grab an air bubble at the surface and then use their paddle-like hind legs to swim to the lake bottom. Even while staying in the water the boatman will swim to the waters surface to grab a fresh air bubble and then back down to the lake bottom. Most of this water travel is therefore almost straight up and down in short jerky movements. The buoyancy of the air bubble makes the trip to the surface much faster than the return trip to the lake bottom, which requires constant paddling.


  • Boatmen prefer the weedy shallows but can be found throughout the lake when flights are occurring. The shallower waters provide more food for the boatmen and a shorter trip to the surface for their air supply. The trapped air bubble allows the boatman to stay submerged for prolonged periods of time. They can tolerate a variety of water conditions from polluted to running waters as well as our lakes.

Importance to Fly Fishing:

  • When I started compiling my fishing records on the computer I was somewhat surprised to find that Waterboatmen were the fifth most important food source for trout in our Interior lakes. Although the boatmen are primarily a food source in the spring and fall, these bugs comprise about 6% of the trout's diet throughout the year. In the spring, the boatmen will get up to 10% of the trout's total feed and in the fall this can go up to about 20% of total feed.
  • The boatmen are available to the trout throughout the year. I have recorded boatmen as a part of the feeding samples in every month but July and I suspect I will eventually get some then. The trout seem to feed on the boatmen more readily during the daylight hours than the evening or after dark.


  • Waterboatmen don't actually have a 'hatch' like Chironomid and many other aquatics, but take flight from the water in the spring and in the fall for mating. This is when the trout primarily feed on them. With their air bubble acting somewhat like a gill, the boatmen will stay submerged and hidden throughout most of the mid-summer months. However, the observant fisherman will see at least a few boatmen in the lake throughout the remainder of the year.
  • Most of our interior boatmen have a single generation per year. The mating flight for those occurs in the fall. However, at least one species has two generations per year with a spring mating flight in addition to the late fall mating flight. This two generation species is generally smaller in size than the single generation species.
  • In the spring the boatmen are actively going into mating flights and being readily consumed by the trout from ice-off until about the first week in May. Naturally this will vary with elevation. In the fall, mating flights at higher elevations can begin by August 23rd and continue through October or heavy frosts at the lower elevations. The average peak for the mating flights often occurs about mid September.


  • I would suggest that you never tie an imitation of a boatman larger than one half inch in length and never with lighter colors on the upper (or winged) portion. With either of those combinations, the trout may mistake the fly for a Backswimmer and actually shy away from the fly. Most of my boatman imitations are about one quarter inch in length and the wings are often just black. If you can, try to tie the fly with a flattened appearance with it wider from side to side than from top to bottom. A dubbed body can be trimmed into this shape and will hold air much like the boatman's air bubble. The paddles should extend out perpendicular to the body and it is best if you can get the ends wide like a paddle. Partly stripped peacock herle seems to work as well as anything. The underside or body can be yellowish, pale green, whitish, or even silver to represent the air bubble. I have even tried Syran Wrap to get the bubble appearance but find the dubbing does just as good a job as anything (until it gets waterlogged) and provides the fly with some buoyancy much like the real bug.

Fishing Tips:

  • Fish fairly small flies (1/4 inch?) tied to imitate the boatman in the spring. The size of fly can be increased in the fall to about one half inch. Try to fish the fly up or down in the water column rather than parallel to the bottom. The retrieve shouldn't be too fast. Try a slow and steady retrieve or try very short jerky pulls to imitate the paddling motion of the bug. You can even fish the boatman as a dry fly and let it sit on the surface for a cruising fish to find.
  • Fishing the fly up or down in the water column is a bit tricky. With a weighted fly and dry line the fly is only retrieved upward in the water. As a suggestion, try tying your boatman as a dry fly or at least very buoyant and fish it with a sinking line. When you cast out, let the line sink while the fly floats. After a bit the fly will sink as it is pulled down with the line. At that point begin your retrieve with very short jerky pulls. It will imitate the boatman as it dives towards the bottom. Continue until all the line is retrieved because the second part of the cast is pulling the fly towards the surface like the boatman rising. This method tends to work better with shorter casts and moderate water depths.
  • Particularly in the fall, and secondly in the spring, the Waterboatmen is a very important food source for the trout. Try some experimentation with your flies and method of fishing. When you find the right combination it can be a very effective way to catch those trout.

Recommended Fly Patterns:

  • Peacock Boatman
  • Deja Vu
  • Orange Boatman
  • Silver Belly Boatman

Be sure to read other articles by Ron Newman

Study Other Insects | Tip & Techniques | Study Fly Patterns

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