Fighting Live Bait Crab

Water boatmen, and their relatives the backswimmers, are present in all of our still waters. Aptly named with their streamlined teardrop shaped bodies and long modified rear legs used for propulsion, they resemble small row boats as they dart away in front of you when wading the shallows.

Although resembling beetles they are classed as true bugs, belonging to the order Hemiptera — meaning half wing. The front half of their first pair of wings being toughened and hard. Water boatmen are often referred to as ‘corixids’, a shortening of the family classification Corixidae.

Water boatmen are primarily vegetarian, though will take small invertebrates when the opportunity arises.

Although almost entirely aquatic, corixids are air breathers. By trapping a bubble of air along the underside of their bodies, they can stay submerged for extended periods of time. Once depleted it must be replenished, requiring a dash to the surface to grab a fresh bubble before retreating back down to the weed beds. Trout that are slowly cruising over weed beds and randomly darting around are often targeting corixids as they head to, or return from, the surface.

While corixids are active year-round, it is in early spring and late autumn that they are of most interest to the fly fisher. Early spring is peak mating time when vast clouds of corixids gather around the weed beds, and they do not go unnoticed by the trout.

Around this time, corixids take to the wing and disperse to other waters. These flights usually happen on calm sunny days, suiting their ability to detect polarized light reflected from smooth water surfaces. On arrival they crash-land onto the surface, before diving towards the bottom. Unfortunately, these ‘falls’ are hard to predict, but can provide some exciting action. These dispersal flights appear again in late autumn/early winter.

Corixid patterns can be fished in numerous ways, usually decided by the activity of the trout. For visible cruising fish, cast far enough ahead to allow your fly to sink to the fish’s level or below. Then raise the fly up in front of them. This upward movement will often be met with a quick take.

If the fish are reluctant to chase the fly or are not readily visible, suspending a corixid pattern under a dry and drifting it around weed beds can pick up fish. Alternatively, if things are very quiet, targeting the slightly deeper weed beds down to six or eight feet can bring dividends. Using a long leader or an intermediate line, slowly retrieve your fly close to weed beds with a short stop/start motion. Takes are often a strong pull.

If you encounter rising fish on one of those bright, flat calm days, it’s worth trying an unweighted corixid pattern. Grease it up so it will sit in the surface film and cast it into the general area. If you can track a fish, try a cast in front, but they can be quite erratic — often it is best to let them come to the fly.

There are a myriad corixid patterns out there, one of my favourites being the Bearded Boatman from the vice of Phil Rowley. It combines the compact tapered body and prominent legs of the natural, while highlighting the trigger-point of the shiny body caused by the trapped air bubble.

Begin by threading a countersunk bead onto your hook, backwards. This has the flatter rear edge of the bead facing forward and gives a wider profile to the head. Then attach your thread behind the bead and wrap a short base partway down the shank.

Tie in a length of raffia on top of the hook shank and wrap down the shank, covering the raffia with a neat layer of thread. You can use one of the synthetic scud-back materials but I like the striated effect the raffia gives under the epoxy once finished. Wrap your thread forward, forming a tapered underbody up to the back of the bead.

Next secure a length of pearl mylar behind the bead, then wrap down the body and back up in slightly overlapping turns. Pulling the mylar tight, almost stretching it, as you wrap will help keep the body smooth. Secure tightly and trim any excess.

For the beard, choose a small pinch of bright mylar type dubbing. Stroke the dubbing between your fingers to align the fibres, and roughly align the ends. Then fold dubbing around your thread and tie in below the hook shank. Once secure, pull the beard down away from the shank and trim, level with the hook point.

Add in a leg either side. If they lay back close to the body, a wrap or two directly behind the leg will help make them stand out from the shank. Once you’re happy with how they are sitting, hold them both back and trim level with the back of the hook.

Then bring the raffia forward over the top of the body, tie down behind the bead and form a small collar of thread. Trim any excess raffia and whip finish to secure your thread. Add a good coat of epoxy over the raffia and bead to complete the fly.

The Bearded Boatman is a versatile little pattern that will cover any situation. This weighted version sinks quickly, ready to lift up in front of cruising trout or retrieve over those deeper weed beds. For a lighter version try swapping in a glass bead at the head. Black or red work well, imitating the two common eye colours of corixids. Glass bead versions can also be greased up to fish in the surface film if needed.