I think it’s fair to say that most flyfishers have a bit of a bug fascination. We see a particular insect, and wonder what’s happening on a nearby trout water.

There are plenty of common, well-known aquatic and terrestrial insects we all look out for: mayfly, caddis, midge, hoppers, beetles, termites… just to name a few. However, in Australia, there are two aquatic insects which fly under the radar for most, being stoneflies and dobsonflies. In this piece, I’ll cover what I know about these often-overlooked beasts of the water and air.

Stoneflies

Some of the largest species favour fast, cold and clean water found only in freestone streams above 700m. Here in the Snowy Mountains we are spoilt for this kind of water, meaning stoneflies are a significant part of the diet of trout. So if you’re fishing these streams, you must be prepared and armed.

Stoneflies can spend years under the water as a nymph, clinging to boulders and feeding on rotten vegetation and algae. Some species are even omnivorous, eating other nymphs and aquatic life.

Depending on the species, stoneflies can be a pretty decent morsel for a trout. Some are up to 5cm, not including antenna. A mature nymph resembles an underwater mole cricket crossed with an earwig. Because stonefly nymphs crawl out onto boulders and dry surfaces to hatch into adults, they are less vulnerable at this stage of their lifecycle than mayfly nymphs ascending through the water column and emerging on the surface. However, the hatch stage is still a moment when stones are at risk of trout predation. Otherwise, they are pretty well hidden and safe unless dislodged via a sudden rise in water level.

I think of an adult stonefly as the Rambo of trout stream insects. Big, bulky and colourful; even intimidating with large wings, antenna and jaws. I mostly see the adults appear early season (October/November) and again late (March/April).

Stones are terrible flyers, and they crash and bang onto the water all the time, especially when depositing eggs. If you see one crossing a river, be sure to observe if it’s noticed by a better-than-average trout.

Do they bite? I have no idea. I haven’t picked one up and don’t plan to anytime soon!

Dobsonflies

Dobsonflies can occupy a very wide range of habitats. I’ve found the nymphs (aka toe biters – yes, they bite really hard) in farm dams in the Victorian central highlands while hunting mudeyes as a young boy, and in tarns near the top of Kosciusko while hiking to the summit. The nymphs are grub-like in appearance with a centipede top half.

Like stonefly nymphs, they are pretty well tucked away as they grow, only vulnerable when dislodged during high flows, or as they crawl to the bank for the next stage of their lifecycle. They just crawl out anywhere! Even onto a barren sand bar where they stick out like… well, you know.

Again, like stones, the adults are clumsy flyers. In fact, they are probably even worse than a stone. I often find drowned adults as a result of their poor flying skills.

You often see adult dobsonflies on a summer evening depositing their eggs at a tail-out, and getting slashed at by the trout while doing so – similar to mayfly spinners. The adults are grey with teardrop wings when rested. They can be mistaken for a stonefly as they look pretty similar. They also have pronounced antennas and jaws. The nymphs bite so I’m assuming the adults do too. Don’t touch. (The bite could explain the ferocity of the take from the trout. Crush and kill.)

Locations

For Victorians, my best stone/ dobson fishing locations were the rivers near the Cathedral Ranges in the Goulburn valley area, with the Rubicon being a standout. Also the Kiewa system above Bogong Dam and McKay Creek/ Pretty Valley Branch. A pattern here is hydro power stations creating artificial nymph ‘hatches’ when water is suddenly released. Fishing dries imitating the adults also be great fun. Big dries for big takes. These rivers alone offer plenty of ‘forgotten bug’ action, and they are just a handful of what Vic has to offer.

New South Wales has a lot of options, but I’ll name just a few favourites. The Snowy River is so diverse. Below Lake Jindabyne, it’s purely mayfly driven. However as you move above the lake, for aquatic insects, it’s about caddis, mayfly, stonefly and dobsonfly. Then from Island Bend up to Guthega, it’s mainly stones and dobsons. Why? Probably because this section is subject to incredible fluctuations in flow: flowless pools to a raging torrent in a blink of an eye. The clingers seem to be one of the only aquatic insects which can hold on here.

The Thredbo River is another. Although it isn’t solely a stone and dobson water, the adults can provide a lot of sport on a summer evening. If nothing else is happening, you can almost count on a savage take to save a donut on the walk back to the car.

A lot like the Thredbo, the Eucumbene River isn’t just about the stones and dobsons. But there are populations of these bugs, and imitations are a worthy choice of fly if not much is happening – especially during higher flows.

The mid sections of the Tumut River are also worth thinking about for stonefly and dobsonfly, including using big nymphs during any sudden releases of water. Fishing adults seems to be more productive while the water level is stable.

Flies and how to fish them

Nymphs

Stonefly nymphs I use vary from commercially-bought to home ties. A favourite of mine right now is the Silly Stone by Manic Tackle, and a Simons Ugly. I also use large Prince Nymphs with good success. I mainly fish heavily-weighted flies due to the fast water and it’s all close contact high sticking. However, if a trout is sighted in a glide for example, I’ll go for lighter nymph. But dry fly first of course!

For toe-biters, a Woolly Bugger or Woolly Worm works well dead-drifted. I have yet to find a commercial pattern, or any kind of pattern dedicated to imitating this insect. If you have one or know of one, I’d like to see it.

Adults

Adult stonefly and dobsonfly are similar in appearance. When covering tail-outs, any of the following could be taken as either insect. My dry fly favourites are orange rubber leg Stimulators in size 10-12, or a Swisher’s PMX in size 12. And flies like a chubby Chernobyl are great.

If searching, I like to fish the dries dead drift at first, then fishing the swing, becoming progressively more aggressive: skating, and then finally, literally popping the fly – stripping it like you’re fishing for smelters down and across! It’s laugh-out-loud fun, especially when fishing with a partner.

I have caught some remarkable fish over the years while going through my stone/ dobson training. The action is too good not to share! Hope you get some inspiration out of this. Duck and chuck some big flies at big targets for big smiles.

Note: Please take great care when fishing below power stations – it can be very dangerous if the water suddenly rises. A fish isn’t worth your life. If this sort of location is on your agenda, make sure you always have a safe exit route, and fish with a partner.