1. Troutnut Forum
›
2. Fly Fishing
›
3. Mature nymphs?

Need help in recognizing mature stonefly nymphs and caddis pupae. With mayflies you can see it from the wing pads, but what about these two?

Caddis pupae is pretty mature anyway, but how can you tell how far is it from the final transition to an adult?

And what about the stoneflies? This is what I'm really interested. There's not that much information on this subject, except for recognizing mature mayfly nymphs.

E

Many mature stonefly nymphs show blackened wingpads just like mayflies. Others don't seem to, and I'm not sure how to guess how close they are except for size.

I think fully developed caddis pupae, the kind you find swimming around, are all very close to transitioning into adults.

Some of the stonfly nymphs will have plump wingpads, alot thicker than in early instars. Sometimes you'll even see the start of a split in the skin, from where the adult will emerge.

Thanks guys.

What about if I dig the pupae from its case, can I see how far it is from a certain characterestic, or just from the general appearence?

Emerger-

I would suggest removing the case from around a caddisfly, rather than trying to dig the insect from the case, as they are relatively soft-skinned and would tend to squish. Once having done so, you should have no difficulty determining whether the inhabitant is a larval or pupal caddisfly, as only the pupal caddisfly will have visibly developing wings. In as much as the pupal lifestage is so short in duration, determining how close pupae are to emergence might be problematic. However, a clue would be the size (relative to mature pupal length) of the developing wings.

Hope this helps.

Is the relative sclerotization of the head capsule indicative at all of pupal age in Trichoptera?

Konchu,

I believe caddisfly head capsules to be fully sclerotized in the larval lifestage. Perhaps I am misunderstanding your question.

Taxon, yes, the head capsules are sclerotized in the larval stage. I am recalling a very casual "gee whiz" observation made about eight years ago. Now mind you, there's been alot of proverbial water under this bridge since then, and some of it may have been effluent. What I remember is dissecting a pupa one time to find the developing adult inside. Parts, but not all, of the adult head capsule were more hardened than other parts. That recollection led me to think now that this might be an indication of how near the specimen was to emergence. Does this make more sense or not? I could be out to lunch on this one.

Konchu,

Haven't dissected a pupa to examine the developing adult. I had assumed you were referring to the exoskeleton of the pupal head capsule. Anyway, thanks for the explanation.