I have purchased the netting at several fabric shops, Walmart may well have it. In 2007 we had a pretty big production of Monarchs and we tweaked the process as we went along. For instance, I do cut the top out of the containers, whether they are yogurt tubs, ice cream pails, ziploc or salad boxes. While it is a little labour intensive at the beginning, I then hot glue the netting over the opening and trim the fabric close to the glue line. "At the beginning" was actually during the winter when nothing else was happening in the butterfly world. I've done this with Starbucks/Tim Horton's large ice capp containers and they work well. Initially I cut out half the lid area only and usually the caterpillar pupated on the remaining half, the solid part of the lid. I then cut around the chrysalid and taped the piece of plastic lid to the roof of our emerging cage which is plexiglass so we can see through it for placement. (It's not a big deal to replace the netting if necessary.) In the case of ice capp cups, they pupate on the netting, and eclose from there just fine. Then the container can be reused. We've had two difficult summers and managed to nurture half a dozen cats only, just enough to feel useful! This year I had eleven chrysalids and four have eclosed successfully. I thought I was done for the year until I watched a female Monarch deposit several dozen eggs in our little milkweed patch on Sunday! Now I have decisions to make....
Back to leaves drying out. The florists' tubes are the glass/plastic tubes which are supplied with corsages or a single flower...they have a rubber cap on them with a hole to push the stem of the flower through. Our local florist gave me 12 of them, rather amused at my use of them. I do use those tubes for stems of milkweed. Typically I place a wet paper towel in the bottom of the container and just lay the leaves on that. If the opening in the lid is sufficient for good air circulation, mold shouldn't become a problem. I change the paper towel and leaves every day anyway.
http://picasaweb.google.ca/fredaholmes/ ... directlink is the link to our online Picasa Web Album which gives a pretty good idea of our technique. One big change though, is that I never allow the containers to become as crowded as I did the first year...we just didn't know enough about keeping healthy cats.
There is an incredible amount of information on this site, describing others' methods or indoor rearing, containers, systems, etc. Just browse the postings and when you find someone whose ideas you like, click on "see all posts by this writer" or something like that and follow their ideas.
Good luck, you're on the right track!
Freda