The booming trout fishing on many south-eastern Australian lakes has seen flyfishers reacquainting themselves with our important lake insects and how they fit into the trout fishing puzzle.

FlyStream has received a lot of requests for information about this lately, so as well as using the search function to check out past articles, here’s a basic cheat sheet to help.

Damselflies

While the colourful and abundant adults (superficially similar to dragonflies) are the most obvious lifecycle stage of damselflies to anglers, the nymphs are by far the most important stage for trout. As damsel nymphs hunt and forage, they are available to trout all year, but it’s when they migrate to shore to hatch during the warmer months – usually during daylight hours – that they create the most action. Unfortunately, unlike most mayfly species, damsels crawl out of the water to hatch, so we largely miss out on an on-water dry fly stage.

Damsel nymphs are long and skinny, and swim with a snake-like motion – often quite close to the surface. Imitations should at least suggest this wriggle when retrieved.

Damsel adults tend to be taken by trout while in flight, and like most ‘leapers’, damsel dry feeders are often difficult and frustrating to catch. However, at times these trout are somewhat more obliging, like when the damsel females are laying eggs on and under the water. So it’s worth carrying damsel dry fly patterns in appropriate colours (blue, red and green are common). The key with these flies is a long, skinny body – trout undoubtedly look for this silhouette.

Dragonflies

Again, the nymph is the big deal: though this time it’s short, stocky and a savage predator, which often swims in jerky jet-propelled bursts. Mudeye nymph flies can be fished at depth all year (bug-eyes are a worthwhile feature).

However, it’s the dusk/ after dark mudeye migrations, particularly on mild dry nights in the warmer months, which are really important. The nymphs swim to shore with their protruding eyes looking for upright structure to crawl out on. Trees and logs are preferred, but mudeyes will settle for reeds, boulders, jetties, buildings… anything upright and dry which will give them shelter during the many night hours it takes for their ridiculously complex wings to form and set.

For this dusk into night fishing, mudeye patterns which suggest the chunky profile of the naturals and sit in the surface, rather than on it, are best. I like foam patterns like the Cubits Mudeye. Retrieve with a figure-8 or smooth draw/ pause.

Oh, and like adult damsel feeders, trout leaping for adult dragonflies are mostly designed to drive us mad, but a big dry with a long skinny silhouette can sometimes work.

Chironomids (midges)

At the other end of the scale to dragons and damsels, midges are often overlooked as very small and (dare I say) boring. But ignore them at your peril: midges are very successful insects which can survive in anoxic habitat few other insects can tolerate, while also being able to cope with extreme cold; meaning they can be active even on alpine waters in the dead of winter. From a trout’s viewpoint, they are often abundant and easy-to-catch; and always very nutritious – three times the protein of steak in every bite!

During their short lifecycle (sometimes mere weeks) midge are mostly bloodworms – red, worm-like larvae which wriggle around on the lakebed, and sometimes drift or swim weakly from place to place. The ‘worms’ are obviously well-represented by long, skinny red flies fished deep and slow: bloodworm imitations are a good indicator fishing option.

When they pupate and swim weakly to the surface to ‘hatch’ out as adults, midge can create amazing action… if not easy fishing! The pupae vary enormously in size and colour, but are very simple in shape, obviously segmented, and with prominent filamentous ‘gills’ protruding from the thorax like white fuzz. Being small and weak, pupa can struggle to penetrate the surface film, and during a mass emergence, the congestion of ‘almost made it’ midge pupa just subsurface, creates a wonderful feeding opportunity for trout, which fin, ‘tail-wag’ and boil… but don’t quite rise.

Depending on the lake, this can happens right through the year; often on evening but also on calm early mornings, and even during daylight – particularly if it’s cloudy and winds are light.

Present midge pupa patterns (ideally the right colour and importantly the right size) with timing and precision as the number of naturals increases and the focus of the trout shrinks. Flies fished more-or-less stationary under an indicator can work well on spooky fish in daylight; otherwise figure-8 retrieve a pair of pupa patterns about a metre apart on a partly-greased leader. For dense hatches, target individual fish aggressively with a pupa about 50cm behind a buoyant ‘pullable’ dry like a Carrot, retrieved steadily to intercept a particular fish. ‘Shotgun’ casting just won’t work.

The adult dries are eaten by the trout too; sometimes as newly-emerged single insects, but more commonly as midge ‘balls’: clumps of midge adults brought together like metal filings to a magnet. Balling midge are mainly an evening event.

Mayfly

I covered these recently – they are after all the glamour insect of flyfishing! On lakes, the nymphs tend to live fairly unexciting lives (from the anglers’ and the trout’s viewpoint anyway) until they swim to the surface to emerge as duns: the drab mini-sailboarders which drift on the surface until their wings are dry enough for a feeble flight to the nearest bankside safe haven. Depending on the year (some are better than others) and the water, lake dun hatches are mainly a late September to early December, then March /April phenomena on the south-east mainland lakes, but more a late spring/ summer thing in Tasmania’s highlands. Humid, cloudy conditions are best, as is roughly the midday to mid-afternoon timeslot, although dun hatches can surprise on both counts.

A lot can – and does – go wrong for the unfortunate junior mayflies in the process of emerging. The nymphs are poor swimmers and are easily intercepted and eaten by the trout as they make their way from lakebed to surface. Once there, the survivors wrestle out of their nymphal shuck with all the speed and grace of a diver removing a wetsuit. These are the ‘emergers’, a few seconds of complete vulnerability beloved by trout and flyfishers alike. Most so-called dun patterns, indeed mayfly patterns, are actually emergers: creations which try to capture those helpless moments when the mayfly can’t swim or fly. Shaving Brushes, Paraduns, Possum Emergers, Barry Lodge Emergers, foam head emergers and even floating nymphs, are all different ways of trying to achieve the same thing. Why some work some days and not others, is often a mystery.

Finally, the last survivors which manage to drift for long enough for their wings to dry, flutter to the bank, and soon shed yet another skin to become a spinner. Dainty and colourful (often black or bright red/orange) these comparatively strong flyers return to mate and soon die on mild to warm days with light winds. As airborne targets of the trout, spinners can be nearly as frustrating as adult damsels and dragons. However, once they lay eggs on the water’s surface or fall upon it ‘spent’, the more quietly-rising trout are much easier to trip up.

Caddis

On lakes, adult caddis are usually pale to white in colour, with long antenna. They resemble moths, but aren’t.

To me, rises to adult caddis on lakes aren’t as big a deal as rises to mayfly and midge. Caddis ‘hatches’ are unpredictable, and even when they happen, they usually occur very late in the day or on the cusp of nightfall.

On the other hand, caddis larvae – and on lakes, these are often stick caddis – are vitally important to flyfishers. While not quite as hardy as midges, caddis can tolerate conditions way beyond the limits of mayfly, including quite brackish water. So caddis, and therefore the ubiquitous stick caddis, can be found on most lakes, most of the year. This makes good stick caddis patterns an essential component of any flyfisher’s fly box. Being fairly weak swimmers, stick caddis flies are perfect fished under an indicator, or retrieved slow and steady as a team, or in tandem with another favoured wet fly.

The Rest

There are of course other significant lake invertebrates which often end up as trout food: water beetles, corixia, aquatic snails, aquatic moths, scud, yabbies and shrimp; not to mention various terrestrials such as beetles, termites, ants, crickets, worms and grasshoppers. However get a good grasp of what’s going on with the insects focussed on above, and your trout lake entomology is off to a good start.