I'd like to improve my understanding of the insects that we try to imitate (sometimes) although on the rivers I now fish close imitation is usually unimportant compared with general impression and accuracy of casting. Yesterday I went fishing with a friend on the Hodder and although it has a reasonably good insect population I haven't seen large hatches of single flies before yesterday. He asked me if I had "seen a hatch of Blue Duns" - as he had - and which I had seen also; large drifts of flies coming off the water. Although the fish were "rising" they weren't clearly taking flies off the top. I did see one nice trout come close to a grey klinkhammer and then pull out and eventually I decided they might be taking emergers a bit deeper - and eventually tempted the fish with a Waterhen Bloa which looked to be roughyl the right size and colour for a drowned fly of the sort which was hatching

This caused me to wonder what people used to match the "Blue Dun" I hadn't seen in "Matching the Hatch" - and concluded by its absence from entomological lists that, unlike the Iron Blue Dun (which is the popular name of an insect) the Blue Dun as such is a pattern, not an insect although the insects coming off looked awfully like the pattern. So what would people use the Blue Dun to match ? I did catch my first river brownie on one 6 years ago but I don't think I've used on since as they don't float for long on the kind of water I usually fish!
GD

I would imagine your friend was talking about the large dark olive GD there aint no such insect as a blue dun. Ive heard guys talking about hatches of "blae and blacks" or hatches of "cinnamon and golds" when refering to the early season black buzzers or cinnamon sedge respectivley.Not strictly accurate, but anglers will relate to that description of the natural insect....if you catch my drift.

Thanks - I suppose it may have been but could it have been the Blue Winged Olive ? They definitely appeared to have powder blue wings!

Round our way GD, I'd be surprised if there was a large hatch of iron blues- they've become really scarce in recent years. The blue dun is indeed a pattern, not a fly, and can be used - like the waterhen - as a general purpose dun imitation.
It's most likely at this time of year that the risers were at either small dark olives, or more likely emerging blue winged olives (which sometimes have great difficulty in shedding their shucks and so get really stuck in the surface film).
Or as Jimmy rightly says, possibly large dark olives, although round here I haven't seen any yet - I'd say it's still a bit early.....

So I would say: if the duns were reet small (say 10mm-ish) then you were looking at small darks or, if they were bigger, then blue wings.

Your iron blues would look tiny and very dark - almost black - in comparison.

M

__________________
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Across the fields of hoar. And the river steamed -
Flint-olive.


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Thanks
Interesting - that might explain why I didn't see the flies being taken off the top if they were BWO's and why the Bloa was more successful - although I would have thought the grey bodied klink would have been OK as the body should have been subsurface (it was more successful with a smaller fish) - may be it was the leader which spooked the approaching fish which wouldn't have been the case withe spider.
GD

Blue wing hatches can be notoriously frustrating! Unlike some of the baetid species of olive (the nymphs of which are classed as 'agile darters'), the bwo is a ephemerella/seratella, and the nymph is what's known as a 'moss creeper'.

When they choose to emerge, the nymphs sort of 'flex' their way to the surface, much in the same way as a buzzer on a stillwater....so they tend to linger around subsurface for longer than their more nifty brethren - hence the 'bulging' rises you describe. It my appear that the fish is taking off the top, but in actual fact, they could be snaffling emerging pupae from as much as six inches below and still create a rise form of sorts.

If you hold a sample net in the current at these times, you'll find you get semi-emerged duns with the dark pupal shuck still stuck to their arses. I believe it is this stage of the hatch which causes us problems - even a klink is likely to be riding too high and the best solution - unfashionable as it might be - could be to fish upstream wet with a single waterhen as you describe.

Spinner falls are another thing. Don't even get me started on bloody spinner falls!!

__________________
The sun pushed dark spokes of melt and sparkle
Across the fields of hoar. And the river steamed -
Flint-olive.


http://northcountryangler.blogspot.com

That's really helpful - many thanks Edenangler. You may have helped me acheive the ideal. I work with a lot of academics sometimes - and they try (sometimes) to make work in practice what they have made work in theory. On the other hand I like to make work in theory what I have observed working in practice!

...oh and what is the problem with spinner falls ..? I have seen some but never really made any progress with imitating them because I don't think I've ever seen enough to get the fish switched on to them - or they haven't appeared to.

Thanks again
GD