I used coir for rooting this last batch of cuttings, and it worked great. The cuttings were in clear drink cups placed inside humidity domes with heat mats. I could see the nice big roots through the cups. Once the roots were looking really nice, and the cuttings sprouted leaves, I potted in 1-gallon black plastic, and was keeping them indoors in clear plastic storage boxes. I watered them when I repotted, but no heat mats, just humidity from being inside the storage boxes and I "aired out" the boxes daily. That's when I began to notice a couple of the cuttings starting to look wilty. I thought maybe it was a bit of shock from repotting, so I left them alone thinking they'd recover in a day or two. Then, another couple of cuttings started to wilt. This didn't happen with the cuttings I rooted outdoors last September. It didn't happen with the ones I rooted in ziplock bags. I lost a few and I still have a few that might survive. They've lost leaves, but the branches are still green and not dried out so I remain hopeful. I pulled one of the rotted cuttings up, and that's when I discovered the larva. There were no roots at all on this cutting, which had a lot of really good roots when it was in the plastic cup. Gnats ate all the roots from the cuttings, so the plants just wilted and rotted.
The weather has been in the 60s, a couple of 70s so I've been lugging them out onto the patio during the day so they get some sun. Nights are high 40s, and I am covering them at night. I have started to use 1 tablespoon H2O2 in a gallon of water. So far, my fingers are crossed, but it is looking pretty good.
I'm not a big one for using pesticides. I'd much rather try to prevent them.