Cranefly Hatch

I was out at a local wetland a few days ago and was witness to a small cranefly hatch. Most people have seen an adult cranefly and may not even know it - they are most often mistaken for giant mosquitos.

Craneflies (Tipulidae) are two winged insects in the Order Diptera (true flies). This order not only includes the family Tipulidae, but also a few families more familiar to fly anglers: Midges (Chironomidae) and Mosquitos (Culicidae).

Like all Diptera, craneflies undergo complete metamorphosis. They start out as wormlike larvae burrowing in mud or damp soil where they feed on decomposing debris (although a few species are predatory - eating small worms or midge larva). The terrestrial or shallow water habitat of most Tipulidae larva make them unavailable to trout most of the time; but they can sometimes be found in the drift during high water. Their large size (up to 50 mm long) make them a tasty mouthfull to any trout, and a larva pattern can be effective as stream levels drop after a rain.

Tipula sp. larva from the Red Deer River

When the larva matures, it will enter the pupa phase. Many species pupate in damp soil along the stream bank or lake margin while others pupate under logs or rocks just below the waterline. Emergence is an event that trout rarely get to witness making emerger patterns inconsequential. The large adults can sometimes be seen clambering along the water surface and are sometimes taken by trout opportunistically.

Tipulidae (just starting to emerge)

You can see the pupal shuck just under the waters surface on the left

Tipulidae (emergence almost complete)

Tipulidae (teneral adult) shortly after emerging &
waiting for wings and exoskeleton to harden

Tipulidae (adult)

Tipulidae (male & female in copula)

I did not collect a specimen so I can not say for sure what the genus or species is.

Last Weekend Update (albeit a little late)

This past weekend saw some interesting if not difficult fishing. With the bright sunny weather, hatches did not materialize to the extent I had hoped. I fished well into the evening but the sporadic action of the afternoon actually slowed down as the sun sank to the horizon.

Early afternoon on a small crystal clear brown trout stream resulted in a few spooked fish and no hook-ups. Bug activity was almost non-existent; I did see a few winter stoneflies lingering along the banks (female Zapada cinctipes waiting to drop the last of their eggs) but no fish rising.

Zapada cinctipes (adult female)

I moved lower in the watershed where the water was just a little on the murky side. Here the occasional fish could be seen slashing at Corixids as they landed on the water and tried to penetrate the surface tension. I worked a backswimmer pattern with a foam back just under the surface and managed to connect with a few good fish.

Around 5:00 a slow hatch of dusky gray BWO’s started to trickle off. Rising fish were few and far between, and those that were rising were doing so sporadically. After a couple of refusals to my usual BWO emerger pattern I managed to hook a few fish on a gray version. I was hoping the hatch would pick up as the evening progressed but things went flat.

Baetis Emergers (Blue Winged Olives)

With Blue Winged Olive hatches starting to make their mark on most open streams, I thought it would be a good idea to cover the next phase in the life cycle - Emergers (click here for a review of the Baetis Nymph).

Emergence is the point in the mayfly lifecycle where the nymph undergoes its penultimate molt into the first adult (dun) stage. As with most mayflies, BWO’s emerge mid-stream – the nymphs rise to the surface in a half swimming, half floating manner. Once at the surface, the nymph hangs there in a near horizontal position while the cuticle splits longitudinally at the thorax and the adult literally crawls out of its skin onto the water’s surface. This process usually takes several seconds and is sometimes complicated by the adult getting stuck part way out (stillborn). Emergence is the most vulnerable stage in the mayfly lifecycle.

In the hour or so leading up to emergence, the nymphs become more active as they jockey themselves into position in preparation for the event. Some will even make a few trial forays off the bottom before they make their final ascent to the surface. At this time a Baetis nymph worked in the middle to lower levels of the water column can be devastating. As the hatch proper gets rolling, trout will often focus on the nymphs as they near the surface. Again, a Baetis nymph suspended a few inches under the surface will produce good results.

Once the hatch is in full swing it will usually be the emerger that gets the most attention.

If you imagine what this stage might look like to a trout you would likely come up with some kind of nymph/adult fusion fly – and that is exactly what most emerger patterns look like. There are several BWO emerger patterns listed in the fly tying literature, and a few available at your local fly shop. But the pattern I like to use most often is a simple modification of my Baetis nymph pattern:

Baetis Emerger (deer hair wing)

Hook: Mustad 94840 (or equivalent), #16-18

                                    Thread: 8/0 medium olive

                                    Tail: olive Antron

                                    Abdomen: medium olive dubbing

                                    Rib: white thread

                                    Thorax: medium olive rabbit dubbing (a few hairs picked out as legs)

                                    Wing: natural gray deer hair or CDC

Baetis Emerger (CDC wing)

The Antron tail imitates the translucent portion of the empty nymphal shuck as the adult works its way free. The deer hair or CDC wing represent the adult that is just starting to emerge above the surface. When fished properly this fly should sit with the nymph portion of the fly just under the surface, being held afloat by the deer hair or CDC. To accomplish this I apply dry fly dressing to the deer hair only (the CDC pattern is fished without dressing). I also make sure the Antron and dubbed body are wet before fishing the fly (I will often apply saliva to ensure surface penetration on the first few casts). Note that the fly will still hook fish even if it does land askew. I use the CDC version on flat water and the deer hair version on rough riffles and runs; although the deer hair version will usually work on flat water as well.

The olive/gray color combination will match 70% of the BWO hatches you may encounter but there will be times when the naturals do not live up to the blue winged olive designation. This past weekend I fished a slow trickling hatch of tiny dusky gray Baetis mayflies. My traditional olive/gray Baetis emerger pattern was refused several times before I switched to a more exact gray/gray emerger pattern – after this, the takes came consistently on the first or second cast to rising browns.

Weather tends to play a key role in BWO hatches. Some of the best Baetis hatches are on days where the weather is less than ideal. Days of unstable weather with a mix of sun and light rain squalls are ideal – most of the action will be from mid-morning to late afternoon. Never let foul weather deter you from following through with your fishing plans.

Jumping the Gun

With the less than stellar forecast for southern Alberta on Saturday I thought we would head up to Chain Lake for the day. A picnic and some sight fishing along the shoreline was the plan. The weather on the drive up looked promising with a little sun peaking through here and there, but I started to have doubts when I saw ice still on Baptiste Lake. Sure enough, Chain Lake was still locked in winters icy grip.

Chain Lake near Athabasca

A few other vehicles with boats arrived while we were there in hopes of some open water angling - but like us, they left dejected.

Ice auger and a boat - these guys came prepared for anthing.

There was a narrow strip of open water along the shore and I am guessing that with this weeks warmer weather, next weekend may see the lake ice free.

A Face Only a Trout Could Love

I captured a few shots of Drunella grandis nymphs from Stauffer Creek this past week. This hatch (Green Drakes) won't start rolling till June on Stauffer, or into July on higher elevation trout streams, but the nymphs can be effective at any time of the year.