Saturday, January 24, 2009

Stuart Crofts' Agapetus Emerger.


I had the pleasure of meeting top river angler and entomologist Stuart Crofts earlier this week. He was guest speaker at the Bolton Fly Tying club and gave a very informative presentation on angler's entomology through the year. Stuart's extensive knowledge has been gained from years of close observation - closer observation than many of us are capable of. Some of the points he made certainly unlocked a few mysteries and I think we all left the place with some real food for thought.

One of the most intriguing subject matters of the evening was the importance of the agapetus caddis. I for one have totally ignored this common little sedge....and it seems that may have cost me a good few fish over the years. Have you ever noticed the marginal stones of your local stream to be covered in tiny gravel shelters in their thousands? I had many times, but I have to admit that I assumed they were immature lavae that would eventualy migrate down beneath the stones to grow to the size we anglers more commonly associate with cased caddis species.
Wrong! These little dome shaped cases contain tiny pale coloured grubs which are in fact, fully grown agapetus larvae. And that is where they stay until ready to emerge.

Now the important bit: when these caddis choose to leave the safety of their case, they scoot up to the surface using a well-defined pair of 'rowing legs'. From here, they swim like mad towards the margins where they crawl out onto a rock to emerge as the adult. It is this stage, when the pupae are held beneath the surface meniscus, that they become a target for trout.
How many times have you fished a spinner fall amongst gently sipping trout, only for an occasional fish to energetically hurl itself at something just below the surface? In times like that, I have sometimes had partial success fishing a balloon caddis; but more often than not, I have left the river feeling like I had failed to make the most of a great opportunity. It seems the agapetus may have had something to do with this - these are small flies (size 20 hook) and a #14 balloon caddis isn't really the right medicine!

The artificials you see above are my attempts to copy Stuart's own pattern with which he has had great success over recent years. Next time I'm standing in a river at dusk on a warm June evening scratching my head in frustration, one of these little devils is going on the leader. I look forward to testing them for myself.

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Another interesting point to come from the presentation was the appearance from the fishes' perspective, of the emerging olive. Stuart showed us some fantastic underwater slides of a large dark olive on the point of struggling free from its nymphal shuck. A definite silvery sheen could be seen along the abdomen as a layer of air formed between the insect's abdomen and its soon-to-be abandoned shuck. Needless to say, Stuart's artificial took this into account by introducing a translucent underbody of silver tinsel to an otherwise fairly standard emerger pattern. An underwater shot of said imitation looked remarkably similar to the natural.

My variation on this theme can be seen below. It doesn't show up too well in the photo, but once that abdomen is damp, it looks very enticing indeed. Could this simple modification make all the difference? I'm not sure, but it will be interesting to find out; the hatches of LDOs on my local River Ribble were very good at times last February. As soon as weather permits me the chance, I will be eager to return to try and winkle out a few late season grayling.


Regular visitors here might recall my blog post of June 2007 when I discussed Stuart's work in adult caddis fly monitoring and how more volunteers were required to send samples so that an accurate 'map' of caddis species, distribution and flight times could be collated. Well in the period since then, the scheme has grown considerably and last year's collated results occupied no fewer than 19 pages. Stuart is one of the most enthusiastic anglers I have ever met and will welcome newcomers to sampling with open arms. If you fancy joining in, get in contact with him via the adjacent link and you will be contributing to one of the most innovative and valuable schemes in British fly fishing today.

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