A.australis Lambda Dun
Atalophlebia australis - Female

"Fly Talk" Freshwater Fishing Magazine
#112 January/February 2012

Mick takes a close look at one of our
most common and reliable duns

After thirteen years of drought the lakes of western Victoria are once again producing some great fish.  It only took less than a year for a number of them to produce kilo plus fish from fry.


What was also amazing was the amount of fly life that appeared, seemingly from nowhere.  Lakes that only a few months earlier had cattle grazing on them were alive with mudeye, damsel fly, midge and mayfly.


The most important species for our lake anglers is the Lambda Dun (Atalophlebia australis) which is also known as March Brown.  Without question this iconic mayfly has been imitated more than any other Australian species.


This species was first described by Walker in 1853, calling it Ephemera australis and it was he that first used the term “lambda-shaped” within its wing pattern, that being the inverted “Y” that is so distinctive.   Lambda is the Greek name for the letter Y - Lambda (uppercase Λ, lowercase λ; Greek: Λάμβδα or Λάμδα, lamda or lamtha) is the 11th letter of the Greek alphabet.

It is found in South Australia, Victoria and Tasmania with a question mark over New South Wales; however, they are well known to exist up on the Monaro streams.


It emerges from around October on and has the habit of coming off from around 11am until about 3pm which is often referred to as gentleman’s hours.


A few years ago I was watching these mayflies emerge up at Harcourt Reservoir in central Victoria.  Interestingly all you would see is a little black bubble which was the thorax of the emerging nymph sticking through the surface.  It stayed there for just a few seconds holding its body down on an angle to allow the dun to escape. A few seconds later the dun emerged and it stood there briefly resting on its shuck.  As the dun stepped off the nymphal shuck it drifted up to lay horizontal on the surface.  There were a couple of lessons to be learnt here; firstly, it was the angle of the emerging nymph and how it bent its body downwards to allow the thorax to push through the surface film. And secondly, the speed in which the dun emerged; it was all over in a second or two.

Cluster of A.australis Nymphs
A cluster of A.australis Nymphs

The All-rounder Nymph - as designed by Mick Hall


Hook:   Mustad R72 2xlong

Size:  14-12

Thread:  Dark Brown 8/0

Tail:  For the All-rounder nymph, three or four strands of Moose mane fibres

Body:  Mottled brown nymph blend

Ribbing:  Stripped peacock herl

Wing case:  Mottled brown Turkey tail fibres treated with flex cement and Loon UV clear fly finish over wing case

Note: The fully formed wing buds indicate that this nymph is almost ready to hatch.

The nymph of A.australis belongs to what is loosely termed

‘the crawlers’ (Leptophlebiidae)

Right:  The Brown Lambda Nymph, or the

              All-rounder - as designed by Mick Hall

Fishing the All-rounder Nymph is as standard, be it a dead drift or slow strip whilst searching for the elusive trout before or after the possible hatch occurs.


However, fishing the Pre-emerger is another question.  Often mayfly nymphs make trial runs up to the surface; this is typical of that last instar.  The wing buds are fully formed and the thorax has turned black as if ready for the adult mayfly to emerge.  In fact the whole of the rotting shuck goes a little darker, hence the darker brown dubbing for the body and the black foam for the thorax.  This pattern is meant to be fished during a hatch and it fishes best if kept right up near the surface.


If you study a hatch you will notice that during a medium to heavy hatch, there will be lulls in the proceedings.  What actually happens is all of a sudden the duns tend to disappear just for a while and a few minutes later they are back.  During these lulls even the fish stop rising but in fact they are still feeding but lower in the water column chasing the pre-emergers that are either rising up and down in that water column or simply hovering.


Some Fishing Tips

You must grease your leader tippet well so that it assists the Hydrostop water repellent and the foam wing because neither the foam or repellent will do it by itself.  The whole idea is to keep your fly near the surface.  Even a large, dry fly used as an indicator will be a great help.  Keep your rod tip pointing at the fly and hold your concentration.  This method works well in both Victoria as well as in Tasmania.


It should also be noted that whilst fishing just about any of the highland lakes you may experience up to three species hatching at the one time; those being the Lambda Dun, The Highland Dun and the Penstock Brown.

Lambda Pre-emerger - as designed by Mick Hall


Hook:  Mustad C49S

Size:  10

Tail:  Moose mane

Body:  Dark Brown nymph blend

Ribbing:  Stripped peacock herl

Wing Case:  Black Evasote soft foam available from Tiewell.


Note:  Treat the finished fly with Loon Hydrostop; this is a water resistant treatment to assist the fly along with the foam to sit in or near the surface film.

Right:  The Brown Lambda Pre-emerger

                       All-rounder Nymph

As you can see they are very similar and their nymphs are also dark brown.  I must admit this multiple hatching is not all that common but we can live in hope.  This is why I call the flies of the Lambda Dun the All-rounder.

The Penstock Brown

Part Two - the duns and the spinners and a more than feasible answer to that argumentative question, “are the spinners actually red or are they orange”?

The Highland Dun
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