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Fly Fishing

> Barr Graphic Caddis Emerger And Similar Ties

My feelings are hurt, Bruce... Didn't you read my posts in the other thread still up? ;)

" When pupation is complete the caddis emerge as adults enclosed in a temporary integument. These are known as pharate adults, though anglers frequently refer to them as pupae. The pharate adults use their jaws to cut their way from the cocoon and case. Then they swim to the surface to emerge, or crawl from the water up plants, stones, or other structure bridging the meniscus. The pharate adults of many species have long median legs fringed with hairs. These paddle like legs allow them to swim effectively. Their wings and antenna are usually folded back along their abdomen. The pharate adults are coloured shades of green, orange, cream, brown or grey. Their thorax and folded wings often appear much darker."

The article by the Norwegian biologist intrigued me, so I did some follow-up research of my own, including some correspondence with entomologists at several American and British universities, as well as the British Natural History Museum. I was surprised to learn that the gas bubble effect was not documented in any scientific literature that I could find, and neither the biologists I corresponded with nor their colleagues had any knowledge of it, nor could they find any reference to the phenomenon.

p127 The caddis emerger, at least those observed by science, does not ascend to the surface by the buoyancy produced by this bubble, it swims or crawls its way up. Finally, like all insects, the pharate caddis splits and sheds its exoskeleton through a combination of blood pressure and muscle contractions. It withdraws its fully formed legs and antennae from their chitinous sheath.

p127 cont The gas bubble phenomenon is undocumented in any scientific study because pharate caddisflies don't exude a gas that creates a bubble between their instar cuticles. The insect doesn't pump itself up like a miniature balloon. As far as we know, no insect does, and caddisflies are, after all, insects. The nearest thing to itis a gel-type molting fluid that the insects produce to help them ease out of the pupal skin, but this lubricating substance is a microthin layer between the two cuticles, not a visible bubble.