My family and I have been having some trouble with some little gnats. We never gave it much thought other then thinking that they were fruit flies because they showed up in the summer when we had fruit and veggies out.
Well apparently they originated from my orchids. specifically one that had very very bad drainage. Bad to the point of being full of water even thought there was a hole in the pot. One night I happened to re-decorate my room and had moved all the pot up but this one because I wanted to put it in a bigger pot.
Now, a little info on this gnat. Apparently they eat the roots of orchids and live in decaying plant matter. They can quickly spread to other orchids and plants that you have. The larva are clear or white-ish and hide in day light and they hatch in three or so weeks. Because they damage the roots orchids can drop their blooms and possibly die if it gets really bad.
This is important because the pot I now held in my hands was heavy from all the water and hundreds of the little suckers were squiggling around in front of my nose. I am not good with bug. I find them insanely interesting but if they surprise me I will scream and freak out like a little girl. So while I did not throw the pot across the room I did flip out a bit and was swearing like a sailor.
This Particular orchid had bee doing very well but all of it's buds had died that week. I had just assumed that re-potting it would fix it. Because there wee so many bugs in it and the roots looked so bad I decided to toss it. It was a clearance plant that I got for maybe $3 bucks so no big loss.
Worried about my other cheap orchids I searched online for what the bugs were and how to kill them. I didn't want to deal with hunter bugs, poison or glue traps and fortunately someone said that you could wash the roots off and re-pot them. Which is what I ended up doing.
I took all my surviving orchids, including the ones in bloom, and took them out of their pots and washed the roots with warm-ish water. NO SOAP!! then i cleaned the pots out with near boiling water and still no soap. I then filled the pots half way with non-biodegradable packing peanuts and sphagnum moss. This keeps the pots insanely dry so I have to play around with the watering.
We haven't had a gnat since.
Now, I manhandle my orchids a lot. This does not make them happy. two of the ones in bloom dropped their flowers because I know i smacked the blooms on the cabinets while working and not because of the root trimming. The cheap orchids that I got happen to be a hardy variety. The beginner variety as it happens to be.
Regardless, unless you have an orchid that dies at the thought of being unhappy, I highly recommend washing roots and getting new potting mix to get rid of the black fungus gnats.