Nymph / Emerger / Dun Size Consistency?

[Fletchfishes 0]

I'm curious - if you are seeing certain size dun on the water, would you expect the nymphs and emergers are the same size?

 

For example, water I'm fishing has a size 18 Sulphur Dun in the evening. Figuring that tying up some nymph and emergers is in order to supplement the Duns. Should I be tying size 18 nymphs and emergers or something larger?

 

Expanding - does this size consistency vary by insect? For example, does a size 12 Caddis larva produce as size 12 Caddis adult?

 

Thanks!

[phg 0]

The nymph is usually a bit larger than the adult, so I would tie the nymph one size larger. The emerger, I'm not so sure of, but I would probably stick with about the same size as the adult.

 

On the other hand, nymphs generally stay in the water for as much as 2 years before hatching into the adult. Consequently, at any given time, there will be all sizes of nymphs in the water, so it could work well to have a 16, 18 and 20 of the same nymph pattern.

[Simon Lidster 0]

In general the most vulnerable time for a nymph is when it's leaving the river bed, swimming to the surface and emerging. These will be mature adults, so at their largest stage.

 

If the fish are feeding on immature nymphs on the river bed they might well be immature and smaller.

 

Depends on the emergence stage for size! As the nymph reaches the surface it's no bigger, but as the adult fly emerges you've got fly and shuck. so probably nearly twice the length of either individually. Hence Klinks are big flies.

 

Just been to Iceland and observed midges hatching dragging the shuck for a long time before flying off. The trout were incredibly selective and seemed at times to only take these, ignoring all the other stages of hatching!

 

Simon

[Piker20 0]

I have noticed the same as PHG. Nymphs are typically larger. Damsel and dragon flys are exceptions. The caenis, if you have the chance to watch them on your clothing are smaller when they molt into spinners. Suppose thats the same with most flies as you cant squeeze more into the previous skin than it will hold.

I have found with Caddis flies the surface film emerger is not worth fishing as the real ones make the transition so fast. But the rising nymph to the surface is very important and there have been times the only takes have come to a fly moved in that very quick near vertical movement. The actual size of the nymph mattered less than the movement the fish expected.