Fungus gnats infestation

[monivik]

For many years I never had any other plants but orchids, and mostly Phalaenopsis, simply because they were the only ones that survived

So this year I decided that I'm going to learn about plants and really do an effort. I started by buying one plant (I thought let me not do more than one at the time) last May and I got a dieffenbachia. I thought it handy to get one of these self-watering things (it's like a see-through ball with a stick that goes into the soil) especially for the extremely hot summer that we just had. Anyway that ball kept getting empty quickly and I figured this must be because of the extreme heat. So at one point during the summer I got all these little annoying fruit-flies in my house. They were constantly flying in circles around my face and just really annoying. I realized that they were in the 100's if not 1000's around the dieffenbachia.

By searching online I learned that they were not fruit-flies but fungus gnats. I was told that I should separate the plant from other plants, which I did. I also repotted it, got rid of all the soil and just put new fresh soil in it. I stopped the self-watering thing, I just try to keep it dry as much as possible. Oh I also put out fruit-fly traps, they caught a good amount of them.

Although there are not so many of these fungus gnats as there used to be, definitely a lot less, but they're still there. I also just realized that when I picked up the dieffenbachia from it's outside pot, it was full with flies on the inside of the outside pot (hmm, hope you understand what I mean). See I had put a layer of LECA on the bottom of the outside pot, simply because otherwise the inside pot (the one the plant is actually in) would sink down too deep, so to sort of make it come up a big higher. So around the Leca beads.... and all around the side of the pot it was just full with flies. I immediately put the outside pot out of doors (it's really cold outside 9C = 48.2F), and now the plant is just sitting on a plate.

The thing is...I suppose I'll still have to repot this plant again? I probably have to anyway as last time I used garden soil (which was the only one I had) and later I've learned this type of soil is not suitable for house plants. So I guess I better get the right type of soil this time. (I realize this has nothing to do with orchids, but if anyone has a tip, it's always welcome )

The other thing is: I did separate the Dieffenbachia from my other plants (orchids) last summer, but I think I was too late. See I've still got these annoying little fungus gnats flying around my orchids now... and I mean we're in October now. It's not a huge amount of gnats, but there's definitely a few. It's just annoying when I'm sitting at the table in the kitchen about to eat and then one is right in my face. Or when I'm watching TV in the living room.

Should I do something about them or would you say don't bother since it's not a huge amount of gnats anymore?