Fly Fishing New Zealand

Brown Beetle Costelytra zealandica – The Rise and Fall of Brown Beetle

Brown Beetle Costelytra zealandica – The Rise and Fall of Brown Beetle – Night Fishing Near Christchurch by Paul Corliss

Brown Beetle – Costelytra zealandica

It is a black river. A night river. A thick winding slug that I came to love. It is a small North Canterbury spring-fed water and in its depths swirled the object of my visit, the hidden shadows of trout. These type of rivers are abundant in most regions in the South Island and the principles applied in this visit are applicable to them as they are here.

It was just after 9 a.m., a sweet and quiet time, between when the dusk has gone and ink black of the night has yet to shroud the lingering light. Softly slotted between the noisy daytime hours with the busy rush of insect and animal and the quieter more reflective hours of the night. A time when all things seemed to take momentary stock of themselves when I checked my knots and my supply of brown beetle imitations, thick clumps of brown deer hair with a small sharp hackle on hooks of size 14 or 12. Even size 10 is not too big.

In the daylight hours and with the sun on it, the river’ s character was reversed. It became a sparkling river, fresh and clear with none of the sombre feel of the dark time. Constantly flickering with tiny points of reflected light, it had delightful runs that in the height of summer became too thin to hold good trout but they provided clear views of where they were likely to feed come the night.

The brown beetle Costelytra zealandica take flight late November and December, their abundance is dependent on the vagaries of the earlier winter and spring conditions. The bane of pastoral farmers and proud homeowners of close-shaved lawns (rarely anglers’ homes), this member of the scarab beetles starts the first of its four stages underground as clusters of white oval eggs.

“… it became a sparkling river, fresh and clear…” Giles Road, Silverstream.

They progress to a larval stage that lasts nine months and feeds on the roots of a variety of plants, grass included. In September / October they burrow deeper into the surrounding soil before pupating. It is when these pupae hatch in November that we see them commence their dusk swarms as they fly off to feed on the leaves of trees and shrubs, among them the willow being a favourite.

The heat had left the air by now but shimmered faint warmth from the grass in which I now crouched,
knees hurting just enough to remind me of my lack of movement in the last 15 minutes. The high shadowed cloud reflected starkly in the oiled surface. Like a flow of sluggish mercury, impeded only by watercress islands, the night water was unbroken by a beetle’s fall or a surface sip. The streamers and tresses of weed muted whatever flow there was in the tail of the pool. It was as if everything around me held its breath, waiting.

Yet there had been an imperceptible change. Nothing seemed to have changed yet somehow at the very same time, unnoticed, everything had changed. Some unseen switch had quietly flicked. 

The grasses at my feet rustled and trembled. A new noise was in the air, a faint and muffled whirring. Careering from the dark they came, seemingly directionless, the bumbling brown beetles. Thank God for their bumbling, without it I would sit cold, stiff and inactive during this special time. Wings ablur after launching skyward from grass-blade tips the beetles flew awkwardly toward water-side willows to feed. And as they flew they faltered. Bouncing off scrub or blown aimlessly into the flow, the pull of the surface tension like tar, there to scutter helplessly and to awaken the urges that would soon produce a quickening in mine.

Then suddenly, there it was, barely noticeable but unmistakable. A soft kiss on the underside of the surface film, betrayed by faint shimmers of reflected light on cobweb-thin ripples, delicately spreading. A sure rise. Then another and quickly another. The tracery of the rise-rings spread and mingled across the water, became more confident and boisterous as the clumsy flight of beetles increased.

I decided on a regular riser, a trout that had finned softly in quiet shallow water where the brush of a broom bough swept a steady stream of food to the holder of the prime lie. A short 9-foot leader with 5-pound tippet flicked out, no time for too much delicacy here, fish short and creep close. The deer-hair dry hit the water with a satisfying intentional plop and rode high close into the bank. At least I assumed it was, all I could pick out was the slightest reflection of dying light off the coils of fly line laid upon the water.

A vague sixth sense and the surge of water as the trout bulged upward were enough to cock the wrist and raise the rod tip. A solid tug came to nothing as the fly flew high to disappear into a clump of raupo, there to stay. A certain feverishness strikes about now, especially as the season for the beetle is drawing late and the duration of the flight gets shorter and shorter. As it starts to peter out completely the trout response can be all over nearly as soon as it began simply enough time to shoot an urgent cast into the black and the last spreading circle is drifting to nothing before the fly has alighted.

The trout showed briefly, tantalizingly!

A fresh-tied dry was soon back in play, the trout still rose noisily though less frequently now, and I struggled to keep my eagerness in check. It seemed a heavy trout and I needed that strength to bow my rod. The fourth drift brought a heavy boil and a solid take. It never hesitated for a second. A surging reel-whirling run straight upstream left the fly-line snagged and twisted among blackberry and around mud encased boots.

It showed briefly, tantalisingly. A thick back arched clear, seemed to pause as it rolled on the surface. A brown of four to five pound, immense for this stretch, slid through the thick dark water. My rod bent low and the fish, now sparking with full power, shattered the connection without pausing in its flight, fleeting and final. A suddenness that seemed to signal the real night.

I stumbled upstream to a long deep pool that a daylight visit had shown to me a sulking brown under the far bank. These daytime recces are invaluable to give you the lie of the land, the snags and the casting room. In a small bay on the downstream side of a peninsula of watercress, the irregular supping of the trout could be heard, not avid but still on the feed.

Two or three casts pricked into the watercress before I had the right length of line gauged and then I drifted the deer-hair along the bank. A small eddy tugged the dry slightly cross-current. A touch of drag, intentional or otherwise, is not necessarily a bad thing. It can induce the take as the surface disturbance not only attracts the interest of the trout but resembles the vain surface struggle of the real beetle.

The brown must have followed the fly some distance for, as I started to lift the rod to start my next cast, the tip came to a sudden stop. The surface boiled with reflected light as the fish rolled in the take. No need to strike, it had the fly and was not letting go. Alternately stripping and reeling line I had him onto the reel and under control quickly. These trout perform better in daylight, at night they are duller and less frantic. The night gives them fewer clues as to the cause of their predicament and confusion often reigns until they are sliding softly into the net.

In knee-deep mud and water, I had the net quickly beneath him. A deep four-pound fish with crimson night-sparkle from the torchlight. I had promised myself this one for the smoker and the bright salmon-orange flesh confirmed the choice.

Brown Trout caught on a brown beetle imitation. Photograph, Paul Corliss.

The weed-cloaked bed of the river teems with freshwater shrimp (Paratya curvirostris) which feed on bottom detritus and material that accumulates on the leaves of aquatic plants, they then provide abundant food for the foraging browns, though this particular fish was bulging with over a hundred and brown beetle and 60 or 70 horn-cased caddis.

While the dusk and early night produce the best rise there is no need to ignore the dawn drop. As the early light crests the horizon the beetles often drop from their high perch and again become victims to awaiting trout, poised to reap the seasonal bounty. During the daylight hours, a selective trout will often respond to a drifting brown beetle imitation, particularly if you go easy on the floatant and allow it to ride in or just under the surface film. A drowned beetle awakens recent urges and trout will accept the offer after ignoring delicately presented nymphs and tiny emerger pattems.

There were no more rises as far as I could hear. From the thickets of macrocarpa across the river came the hoot of a stirring morepork, the rustle of possum and a dying chorus of roosting starlings from the pines. That time of night when all decent things go to where they belong.

This post was last modified on 13/03/2024 4:11 pm

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