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Windfalls of grubs and cicadas

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Tony Orman

Marlborough writer Tony Orman highlights two summer windfalls of terrestrials that can drive trout to dogged, selective feeding and anglers to despair.

In the warmth of summer, willows get blighted by small red blisters on the leaves. It’s no heat blister or leaf blight but the home of a small whitish grub which, when it hatches, is a light lemon colour.

Within its home on willow leaves the grub grows to about 6mm and then emerges to spin a pupal cocoon on the leaf. The adult is the saw-fly which can lay its eggs inside a plant’s leaf thanks to a serrated edged ovipositor which enables the insect to make an incision so the eggs can be inserted.

When the grub emerges it lowers itself to the ground on a gossamer thread.

However willows often overhang rivers and streams and the tiny grubs fall into the water.

It is late summer when this happens and trout become single focused on the tiny insects and swim just under the surface beneath willow trees slurping up the many willow grubs.

Hooked into a brown that took a cicada pattern. Cicadas are common in wilderness rivers with over-hanging beech forest.

Selectively Feeding

My first experience of the willow grub was on the Maraetotara River in Hawke’s Bay. This limestone stream, which is not really a river in size, runs in slow meanders, often overhung by willows. On this occasion Pedro and I had headed out to the stream to get the morning’s fishing before the afternoon westerly winds gathered pace.

I had fished for an hour for trout I found cruising under willows. The fish fed systematically on something small on the surface. I tried Pheasant Tail and Pheasant Tail variants, Water Boatmen and other tiny dries and nymphs to no avail. The trout were selectively feeding on something small.

I headed back upstream and found Pedro. He had a nice brown trout, had released another he told me, and was now intent on another trout slurping under the willows.

“What the heck are they on?” I asked.

“Willow grubs,” he whispered.

Pedro crouched watching the fish sipping here and there and then as the fish turned away from him, he flicked out a roll cast. His tiny little fly barely sank and the fish was onto it in a flash, its white mouth showing as it took the fly.

“Gotcha!” exclaimed Pedro as he hooked the fish.

He bullied the trout downstream away from the willow and netted a fine 1.8 kg (4lb) brown which he released. I looked at his fly. It was a size 16 simple little nymph, pale lemon in colour and a turn of light small hackle.

“Yep it imitates the willow grub,” he exclaimed. “Tie it on a light hook, the lightest gauge you can get, grease your cast, a dab of dry fly gunk on the nymph’s hackle and fish it in the surface film or as near to it as you can get.”

We sat in the sun and talked about the willow grub.

“What’s its Latin name,” I asked.

“Dunno, haven’t got time for that piffle,” he chuckled. “Besides as noted US writer Lee Wulff said trout don’t know Latin so don’t worry about it.”

In fact the technical name for the willow grub is Pontania proxima.

Trout taking willow grubs are deceptive. They seem to be rising but are in fact feeding in the surface or just under the surface.  It’s easy to use a dry fly. Trout can be very selective; concentrating not only on the one insect but the exact phase or level. In the case of the willow grub, it’s subsurface.

Willow grubs occur in their hundreds and thousands because they are vulnerable in that change from larva to cocoon. Nature compensates by giving the insects a reproductive capacity of massive numbers. The result is great dining for trout!

As I found that morning with Pedro, forget a Pheasant Tail nymph or a tiny Adams dry fly. There’s a 99 percent chance the trout will ignore them.

Pedro told me his pattern was adapted from Norman Marsh’s classic book, Trout Stream Insects of New Zealand. Norman Marsh’s simple wee pattern is -

  • Hook: 16 -18.
  • Thread: Brown.
  • Body: Primrose silk.
  • Head: Brown tying thread or one turn dark peacock herl

Pedro added a half turn of small, light cream hackle at the head “just to help with floatation.”

On the Motueka River in late January and February I often found fish sipping in under willows just as they were that day on the Maretotara.

Because the trout is near the surface and the divergence in its cone of vision is so little you can crouch and just flick or roll cast the nymph into a trout’s path. If the trout does not take first or second time, don’t worry. It’s just there’s so many willow grubs, the trout has to pick yours out!

In late summer I’ve encountered willow grub sippers on numerous rivers in the South Island from the Takaka to the Pomohaka, Mataura, Maruia, Wairau and quite a few others that spring to mind.

The red blisters on willow leaves caused by the saw fly or willow grub.

Cicadas Too

Another summer windfall for South Island trout is the cicada.

Trout just love them!

And for two reasons: they’re abundant and one insect is a big helping, far bigger than say the rough equivalent of 100 deleatidium mayfly nymphs!

Trout are energy conservation conscious. Taking one cicada is just one hundredth the energy expended in eating 100 may fly nymphs or the same amount of food.

I remember one day many years ago - 1969 to be exact - when I fished a tributary of the Wairau River in Marlborough. A good-sized fish was clearly visible feeding avidly in a small pool with a churning, white-water rapid pounding down into it. I began with a stonefly nymph, always reliable on this bouldery river. The trout ignored it. That disdain was repeated with the usual size 12 Pheasant Tail, Hare and Copper, Speckled Nymph and several others. Still the fish fed.

I looked at my fly wallet. I had tried everything - well almost everything - except for a big outsize size 8 Hare and Copper.

I tied it on and put it in front of the trout. In a flash the trout had it and 10 minutes or so later I landed a splendid 3kg (6.75lb) brown. I killed that fish and examined its stomach. Cicadas! There were some two dozen cicadas crammed in its stomach.

The trout had been taking drowned cicadas and it was then I became conscious of the noise the cicadas were making. If only the song of the cicadas had registered earlier!

The male cicadas apparently are the ones that make the noise. In the recently published excellent book, The Trout’s Larder, the noise the male makes is described as ‘Bellowing’!

And  in the South Island and the North Island the species Amphipsalta zealandica is one of a group known as the clapping or chorus cicada.

Another, the Amphipsalta cingulata, occurs only in the North Island. The two species are very similar but have different songs. There are a few other cicada species too, often with specialised niche habitats such as scree slopes. Others live in forests.

These are irrelevant from the practical trout fishing viewpoint. A cicada is a cicada.

A brown cruising under willows looking for grubs

Different Imitations

I have encountered cicadas and trout focusing on them in numerous rivers but I recall on the Lower Matakitaki near Murchison, encountering rising fish on a hot summer’s day and flicking a Muddler Minnow, fished dry, to them. The trout took without hesitation.

You can use a Muddler as I did that day, buy a cicada imitation from tackle shops, or tie up a more specialised cicada imitation.

Again referring to that great book Trout Stream Insects of New Zealand, Norman Marsh gives a cicada pattern as follows-

  • Hook: 8,10 or 12.
  • Collar: Peacock herl
  • Body: Deer hair
  • Hackle: Brown cock
  • Wings: Badger hackle tips
  • Tail: Deer hair

I would suggest tying it on a size 8 and forgetting the size 12.

Tackle shops carry some excellent imitations of the cicada.

Keith Draper in New Zealand Trout Flies gives a pattern as follows-

  • Hook: 6 to 8
  • Body: Red deer hair spun three quarters along the shank and clipped. Another small bunch of hair is spun on and left straggly.
  • Wings: Stiff plastic, veined with a green felt pen
  • Hackle: Long, stiff natural red cock

In Bob Wyatt’s book Trout Hunting a pattern called McPhee’s Wee Muddler is given as follows:-

  • Hook: 10 - 14
  • Abdomen One: Dubbed seal’s fur and possum fur mixture, shades of green mixed to match a particular cicada, tied at the bend of the hook to build up a thick rear portion of the abdomen, to the middle of the hook shank.
  • First Wing: Clump of medium deer hair, tied in at the middle of the shank, tips extending to just beyond the bend, butts trimmed and lashed down.
  • Abdomen Two: Finish building abdomen taking dubbing to near the hook eye, leaving enough space to tie in over-wing.
  • Over-Wing: Another clump of deer hair tied in to lay over the first wing. Butts trimmed to form a Muddler-style head.

Interestingly that pattern is on an unusually small hook, i.e. 14. I would suggest an 8 or 10 hook.

But if you are daunted by tying these patterns or don’t tie your own flies, go buy two or three for your fly box. That’s what I have done once or twice, to save tying a time-consuming pattern. Besides, the shop ones are beautifully and realistically tied.

Rainbows love cicadas too – from a back country stream near Omarama.

Blind Fishing

Ideally cicadas are fished to visible trout but don’t neglect just blind fishing up riffles or pocket water. A friend of mine did this last season because he got cheesed off with the long trudge back to the car after hiking upstream for several kilometres. Instead he tied on a cicada and just systematically fished blind up a couple of pools. The result stunned him - several hefty Wairau browns that he probably would have bypassed in his usual haste to forge upstream.

In swifter water, trout taking a cicada will usually zap the fly quickly and invariably hook themselves. However, in slow pools trout can eye the cicada and then confidently ease up under it, take the fly and roll over. It takes a steady nerve and a lot of discipline to delay the tightening, while slowly muttering “Graham Henry or Robbie Deans?”


  • Trout’s Larder, by Duncan Gray and Jens Zollhoefer, published by Reed Publishing 2006
  • Trout Stream Insects of New Zealand by Norman Marsh, first published 1983 by Millwood Press and subsequently reprinted by Halcyon Press.
  • New Zealand Trout Flies by Keith Draper, published by Reed Books, 1997.
  • Trout Hunting by Bob Wyatt, published by Swan Hill Press (England) 2004

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