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3. Caddis behavioral triggers

Hey, guys. It's been awhile since I've posted - other stuff going on, I guess - I haven't been fishing in ages. Anyway, I'm trying to raise caddis larva (Pychnopsyche) in a tank to make me ornamental cases. Right now, I have a few dozen larva in pre-cases made from leaf litter. They're in a tank in my basement that is holding a cool 44 degrees right now. They seem to be content - I've had some living in there for over a week without any deaths that I can see. I'm wondering how they'll know when to start making cases from the stones I'll be putting in there for them. What environmental triggers are necessary to make them build stone cases? Water temp, hours of daylight, internal chemical signals timed to the seasons... I'm just not sure how to make sure they'll do what I want them to do. Do I have to make sure they're close to a window to get cues from the sun? I mean, how much sun could they get in the stream when they're under a rock? I'm hoping my basement will slowly warm as the weather does, but I don't really know for sure what temps it will hold as the next few months unfold. I was told by an entomologist that it could be important to have a predator present (like a trout in an adjacent tank) to encourage the caddis to defend themselves by building a case. I've also heard that if you make life too easy on them (abundant food, little to no current) they might not feel enough stress to build. Anyway, I just thought I'd put the question out there and see if any of you venerable gentlemen have any wisdom you could share with me to raise my odds of success. I'd like to be successful the first time - another trial would mean waiting another year.

Thanks,
Shawn

Hi Shawn,

Good to hear from you again. I don't know about those other issues you mentioned, save the one that really stands out to me. Sounds like your water is pretty cold. If you get it up into the 50's and provide more light, their development should really speed up. Growth is the biggest impetus to case building. They don't like to crawl around naked.;)

Check with Kathy (http://www.wildscape.com/). She was going to publish a paper on methods but I don't think it has happened yet. Maybe she hasn't because there seems to be some competition developing.

Thanks, guys. I'll try to rig up my tank near a window - that might also help warm the water a little.

I've met Kathy before and originally wanted her to make me the cases for my project, but it never panned out and I thought it would be fun to try on my own anyway. I'm a firm believer that the more of yourself you put into something, the more you get out of it. I've definitely tried to glean as much as I could from her experiences, though. I know of at least 2 other people who have done this as well, and I'm sure there are others. It's a cool idea, but certainly not original to me. The only new twist I'm adding is incorporating the cases into my artistic fly tying. I'll definitely post the finished pattern on Troutnut.

An added bonus to the project is that my younger son Emerson has become quite interested in it. He has accompanied me to the stream both times I've gone to collect bugs, and he's been enthusiastic and patient both times in spite of the temperature and several feet of snow. He was particularly excited about our catching a few stonefly nymphs (including a Beautiful Stone) and a small salamander. So our "caddis" tank has some diversity.

Any additional suggestions welcome.

-Shawn

Yes, keep the Goldens away from the caddis. They are verocious predators. Though their primary diet is usually mayfly nymphs, I wouldn't tempt them.;)

Sounds like Emerson is well on the way to becoming a dedicated naturalist. The fact that he finds watching caddis crawling around on the bottom of an aquarium fascinating is a pretty good sign. It's great that you are sharing this with him.

I look forward to seeing the fruits of your labor!

Dave -

Don't most Psychnopsyche species generally build their cases out of mixed materials, mostly plant in earlier instars? That might be of help to Shawn.

This is really cool! Impressive little experiment that sounds like plenty of fun! This would be something I would like to do with my kids someday when they are starting to fly fish ;)

I tried putting some caddis larvae in my fish tank one early spring, with some random fish my dad had at the time - I think tropical... So the water was quite warm. They lasted a few days to weeks before the were eaten lol

But they did manage to make decorative cases from the blue and red rocks in the tank! The main portion of the case was still brown natural, but there were glittering red and blue specks ~ but this surprised me a lot they would use the artificial rocks to at least some degree

Or maybe the specks just got lodged in the cracks of the casing? Hmm...

Ah! There you go, Shawn. Pick aggregate for "designer" cases that fit the effect you're looking for.

Nick - Caddis are good little architects and make use of what's available. Those colorful stones weren't stuck there by accident.

To get the case you want give them only the material you want in the case. You probably can do that at any time now. I suspect the immature ones can get by with mineral material to. Depending on the species they will build the mineral case they want given the temp, etc. you give them. The biggest problem you may have is probably keeping them cool enough and fed before they pupate.

An alternate approach, if your stream is close by, is check it every week or two to see when they start adding mineral material. Then collect the larvae and give them the material you want. That way you won't have to feed them. They should build the pupal case pretty fast. Even though they close the pupal case it may be months til the emerge, normally near leaf fall in your area.