Gnats in the soil...?
Having just moved into an apartment all on my own, I decided to get plants and we always had some on our balcony when I lived with my Mom. My apartment is actually on the ground floor so I have no balcony, but I figured I could have plants indoors. As na�ve as it may sound, bug infestation never even crossed my mind; now, in barely two months, I've had to treat my plants for gnats, spider mites and mealy flies.
The flies and the spider mites, I'm convinced came with the plumerias I've bought, mainly because they never came close to my other plants (a bunch of succulents, haworthias, mainly, and a couple of adeniums).
I was able to get rid of the mealy flies fairly fast with a homemade treatment and daily observations of my plants; the spider mites, on the other hand, weren't much impressed by anything, so I sacrificed the plumeria they had infested (and that was dying anyway --- from the mites or my treatments or both...).
The gnats, I thought I got rid of when I sacrificed the flowers I was trying (and failing) to grow. They had infested only those and the haworthia I had repotted in purchased soil. As I learned a little too late that cacti and succulents need a special type of soil, I unpotted it, switched to semi hydroponics, and moved it from the living room to my bedroom: I place all the healthy, non infested plants in my bedroom in hope to stop the pest from spreading too all my plants...
The thing is, I'm finding gnats again in the living room... and I have no idea where they come from: I haven't purchased any other plants since I realized I had these pests infestations. They certainly didn't come from the clay pellets and I never, ever see them around the plants that I haven't repotted: I think the soil is too compact. Too dry too. So I doubt they came with the plants...
I do wonder about the window, though... but I have mosquito nets on all of them. Except they're not the finest nets either. And the living room's windows over look a small garden. I haven't really checked for gnats infestation but I don't think there are any, especially as the garden isn't watered much. Not every day, in any case... the soil does go dry between waterings.
The only other thing I see is the soil I've purchased --- the one that's not for succulents and cacti (I'm still a beginning, making stupid beginner mistakes): I had some left in a small container that had a few succulents leaves, experimenting with propagation. I did water it regularly but I think I got the soil a little more moist the last time I did; and shortly afterwards, gnats were in that container and in the adenium's semi hydroponics pot (that one is still the living room).
Now, I'd like to know just how crazy my hypothesis is: that the gnats are actually in the soil I've purchased; not the adult forms but eggs, perhaps. Or do I have to blame the mosquito net on my windows for not keeping the gnats out? I want to make sure that once the gnats are gone, they are really gone (perhaps 'forever' is not very realistic, but I can't have them coming back every month); and I can't do that without knowing where they come from (although if it is from the window, that might be a problem)...
Would anyone care to share thoughts on that...?