October/Fall Caddis Life History?

Discussion in 'Fly Fishing Entomology' started by BDD, Aug 3, 2006.

  1. BDD

    BDD Active Member

    I recently returned from 3 days in Idaho fishing NF Clearwater (fishing was good). Each time I go, I am amazed how how many large cased caddis are clinging to the rocks; they are everywhere and the same holds true for all the streams in north central Idaho. However, on trips later in the fall like September and October, the caddis are completely gone from the shallow rocks where they are located in the summer. I assume they migrate when they hatch but where do they go and why don't you see them? You can find the egg-laying adults in the evenings as they return to the water and there are some fish keying in on the adults. However, at what point during the life stage do trout really key in on the nymphs during their emergence? I have seen cased caddis patterns in fly shops. Are there times when trout eat case, worm and all?
  2. James Mello

    James Mello Inventor of the "closed eye conjecture"

    October caddis are kinda weird caddis as they stay in their cases for a pretty good long time. My understanding is that either the trout eat them, case and all, or they get them as adults. Also, the emerge by crawling from the river bed to the shore and emerge away from the fish, usually at night. This is why you don't see the traditional caddis maddness like you do for other caddis.

    In my experience, you can usually throw a cased caddis imitation in Sept when they are their fattest in riffly water and hook up with fish. The case is big, but the morsel inside seems to be large enough to the fish to warrant eating a bunch of crap with the bug.

    -- Cheers
    -- James

    PS Taxon and others may have more specific info.... Also, read the LaFauntaine book on Caddis as it's a pretty good fishermans reference on Caddis in general.
  3. Taxon

    Taxon Moderator Staff Member


    James gave you good information. However, I’ll expand a bit on their life history.

    October Caddis or Fall Caddis is the common name for Dicosmoecus, one of many genera in family Limnephilidae, the Northern Case Makers. They begin life in the egg stage. Once the larva breaks out of its egg, it builds a case of rock fragments and sand held together by silk extruded from a gland in its mouth, and lives among the rocks in moderate to fast flows of riffles and runs. Sometime around early to mid-summer, it migrates to the slower flows of the stream margin, attaches its case to a rock or woody debris, and begins a two-month pupation phase. Following pupation, the pupa cuts its way out of the case, and crawls onto the above-water potion of an exposed rock, from which it emerges. Following emergence, the adults fly to streamside vegetation, where they mate. The females return to the water one or two days later, usually in the early evening, and deposit their fertilized eggs through repeated landings on the water’s surface, thereby completing their life cycle.

    So, the bottom line is, October Caddis are most available to trout during the pre-pupation migration to slower flows of the stream margin, and during the egg-laying activity, as most emerge out of the reach of trout. Hope this helps.
  4. Preston

    Preston Active Member

    October Caddis ( genus Dicosmoecus, gilvipes is our most common species) are eaten, case and all, but in June and July they abandon their cases and drift before settling down to build new cases. Oddly enough this drift usually occurs during the afternoon and exposes them to predation by trout. It's pretty difficult for a fish to pass up an inch-long larva floating helplessly in the current.

    After pupation occurs, most pupae swim and crawl toward shore though a few simply swim to the surface and emerge there. This may occur as early as the latter part of September and may last into November. Some observers report that the pupae appear to be in no hurry and may spend several days swimming fearlessly in shady backwaters. I can state for a fact that the pupae are a favorite snack for sea-run cutthroat and, back in the day when I was still inclined to kill an occasional cutthroat, I have found as many as half-a-dozen of these large, orange grubs in their stomachs. The actual emergence usually occurs at night and often the streamside rocks and logs will be festooned with an incredibly large number of the pale, pinkish-orange shucks in the morning.

    The male and female adults may live for a week or more after mating and must return to the water periodically to drink. This is a rather clumsy process, as is the female's egg-laying process, creating quite a bit of fish-attracting commotion. Oviposition usually occurs in late afternoon and into the night, but they can be found flying around in the shade of overhanging trees and brush even in the middle of the day.

    Here are a couple of flies that I have used with some success.
  5. Troutnut

    Troutnut New Member

    Preston, where did you find that the actual emergence is at night? Personal experience?

    LaFontaine's Caddisflies says they are daytime emergers and that's one of their charms. I haven't fished the hatch, so I based most of the stuff in my Dicosmoecus page:


    on his book and contributions from Taxon and others.
  6. Preston

    Preston Active Member

    According to LaFontaine, "Emergence begins in late afternoon and continues until dark" (Caddisflies, page 275). Ralph Cutter (can't find the reference just now) says much the same and implies that emergence continues until well after dark. As to my own observations, I have only very rarely seen an October Caddis pupa crawl ashore and begin to emerge during the daylight hours. I have, however, seen streamside rocks and logs liberally covered with apparently freshly discarded shucks in the early morning hours.
  7. Jim Wallace

    Jim Wallace Smells like low tide

    Great thread! Thanks guys!
  8. troutman101

    troutman101 Member

    I've never seen an emergence during the day either. I have seen them emerge in the evening and they fish best just before twilight as a dry fly and the pupas swung in slow waters and deep holes at dawn. Something worth doing is hunting the shores for hatchers and watching them emerge. Kinda slow but still fun.
  9. Smalma

    Smalma Active Member

    Skating October caddis patterns for summer steelhead or sea-run cutthroat can be great fun. There is just something about the caddis's "clumsy" egg laying that seems to excite steelhead. Interestly even tough the adult caddis are only active only late in the day once the "hatch" is several days along the fish will respond to a skated fly all day and will continue to do so well into the fall. The very best fishing is often the first few days after the river has dropped after the first significant fall rains.

    BTW - for what ever reason those fall summer steelhead chasing the caddis also seem to be especially clumsy - not uncommon to "rise" a number of fish in a day and have only 1 or 2 hook-ups. It helps to stay calm and allow the fish to continue to chase and slash at the waking bug until it finally solidly connects - much easier said than done.

    Tight lines

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