difference between caddis pupa and caddis larva??

[steve sullivan]

A couple of weeks ago I was checking out the contents of a steelies stomach. It was all caddis, some things I noticed:
forked tail.
small black head (fox pupa's I see in stores have peacock or ostrich herl that is much bigger than body)
2 prominent pairs of arms, legs were not prominent (pupa patterns have prominent legs).
bugs were pronouncedly curved

Were these caddis larva? What are the differences between pupa and larva? How come caddis pupa imitations dont have forked dark tails?

[Digger]

a prominent forked tail seems to indicate (to me) a stonefly?

[Darian]

This is not gonna be very scientific but, larval stage of caddis is begins upon hatching from the egg. They look a lot like a worm, inhabit the bottom and may be a free living form or case builder. Not overly mobile (cannot swim). 8) At some point they spin a cocoon like net or case and change/molt/pupate. When they emerge from that state, they're a Pupa. The pupa is the emerger stage that swims to the bank or surface and prepares to fly by molting to become an adult. 8) 8)

Not sure whether caddis have both, "arms" and "legs".... :lol: Legs are prominent on the emerger (folded) and adult. The female adult has a forked tail (not prominent :? ). The abdomen is segmented and curved. 8)

Having said all of this, it's my opinion that it's not overly necessary to be absolutely perfect in attempting to imitate a caddis or any other bug. After all, the best fly tied is still not as good as the original..... 8) 8) :D

[Hairstacker]

Darian, for not scientific you were dead-on accurate! Just to add to what you said, the larva undergoes a complete metamorphosis during the pupal stage, during which it is essentially in a coccoon transforming from a larva into a complete, fully-formed adult. The pupa emerges from its "coccoon" as a fully formed adult caddisfly encased in a thin pupal outer skin or "shuck." Thus, Steve, since the adult caddisfly doesn't have a dark forked tail, the pupa doesn't either (although I don't believe any of the larva have dark forked tails either). Encased in this thin skin, it swims/floats to the surface and it is this stage (when it's swimming/floating to the surface) that we imitate using pupa fly patterns, as it is very vulnerable to being eaten by a trout during its swim/float from the bottom of the stream to the surface. Once at the surface, the adult caddisfly "emerges" from this thin skin and flies away. Which is why we also have caddis emerger fly patterns with an antron tail to suggest this pupal skin or "shuck" from which the adult caddisfly emerges and flies away.

Steve, I believe Digger is right, if you see a prominent forked tail, you are looking at a stonefly nymph of some sort, not a caddisfly larva, and if the forked tail involves 3 prongs, you're looking at a mayfly nymph. Dragonfly and damselfly nymphs also have 2/3-pronged tails, by the way, but they don't fork out as large and prominently in relation to body size as, say, a stonefly nymph.