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> > Behavioral Drift - With or Without Case?



This topic is about the Insect Order Trichoptera

Some say caddisflies are even more important than mayflies, and they are probably right. The angling world has taken a while to come to terms with this blasphemy. Caddis imitations are close to receiving their fare share of time on the end of the tippet, but too many anglers still assume all caddisflies are pretty much the same.

Caddis species actually provide as much incentive to learn their specifics as the mayflies do. There is just as much variety in their emergence and egg-laying behaviors, and as many patterns and techniques are needed to match them. Anglers are hampered only by the relative lack of information about caddisfly behavior and identification. Read more...

Rhyacophila fuscula (Green Sedge) Caddisfly Larva Rhyacophila fuscula (Green Sedge) Caddisfly Larva (11 Pictures)
Brachycentrus (Grannoms) Caddisfly Pupa Brachycentrus (Grannoms) Caddisfly Pupa (10 Pictures)
Hydropsyche aenigma (Spotted Sedge) Caddisfly Adult Hydropsyche aenigma (Spotted Sedge) Caddisfly Adult (18 Pictures)
Dicosmoecus gilvipes (October Caddis) Caddisfly Nymph Dicosmoecus gilvipes (October Caddis) Caddisfly Nymph (3 Pictures)

There are 124 more specimens...

The Discussion

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DaveCJune 18th, 2007, 1:17 pm
Posts: 2The definition provided by Jason suggests that Behavioral Drift occurs when cased larvae simply "let go" of the stream bed, rocks, plants, etc. and drift while still encased within their cases. However, I always presumed the case, or test, was specifically constructed from material that added "ballast" to the grub and therefore prevented it from being swept away in the current.

QUESTION: Do larvae ever crawl OUT of their cases/tests and drift "naked" until they settle somewhere downstream, and then begin to build a NEW case/test?

It would be useful to know whether a "behaviorally drifting caddis" larva pattern should imitate the appearance of a case or test that's constructed of sand, leaves, twigs, etc., or whether it should instead imitate the appearance of just the naked grub.
GONZOJune 18th, 2007, 1:36 pm
Site Editor
"Bear Swamp," PA

Posts: 1681		Short answer: As I understand it, yes, some behavioral drift of case-building caddisflies is caseless. (Glossosoma and Dicosmoecus larvae are two examples that come to mind. I'm sure there are many others.)
TroutnutJune 18th, 2007, 1:55 pm
Administrator
Bellevue, WA

Posts: 2737		Yes, some of them do drift without their cases. Gary LaFontaine in Caddisflies mentions imitating the un-cased drifting larvae of otherwise case-building caddisflies in at least a few places.
Jason Neuswanger, Ph.D.
Troutnut and salmonid ecologist
JeffKJuly 3rd, 2007, 12:49 pm
Hackettstown NJ

Posts: 1		One October on the Beaverkill the rocks were covered with a sand cased caddis. When I tried to catch them they scooted away and I couldn't catch them by hand. I was surprised that cased caddis could be so frisky. The cased caddis I see in the spring are easy to catch by hand.

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