Has anyone used diatomaceous earth with their carnivorous plants?
For anyone unfamiliar, diatomaceous earth is a dust that's not harmful to humans but easily destroys insects' exoskeletons and respiratory systems. I have an issue with gnats and happen to already have some diatomaceous earth for an unrelated purpose (well, still for killing bugs). The idea is that a layer of diatomaceous earth atop the soil prevents the adults from landing on the media to breed there without dying. Would this be harmful to my plants in any way? Would I need to wash the diatomaceous earth before use? If you've tried this what were your results?
The plant that appears to be harboring the gnats is a VFT that came from a hardware store death cube (although they might be in the other plants too). It's done fine over the last few months and although its growth has slowed, it hasn't gone fully dormant and likely won't this year. To my surprise, when I was inspecting the plant I also found a number of small sundew seedlings. Apparently some capensis seeds made their way into the VFT's pot. The sundew has done a good job of catching the adult gnats and is doing great, but I'm concerned about what the larvae must be doing to the plants' roots.
So, the question is how to vanquish the gnats without damaging the VFT or the seedlings. I don't want to transplant the seedlings at their current size, and I'm concerned about infesting a new pot with the present larvae anyway. Of course, I'll eventually be repotting with carefully rinsed fresh media. In the mean time, I want these things gone!