Caladium Pest (Trying to Take) Control

Almost since I brought this plant home it has had a problem with this gnat-like insect spreading over its stems and in some cases the undersides of the leaves.  I have tried googling this problem, but I am having a hard time identifying the pest and therefore effectively eliminating it.  So far my method has involved drenching the plant with my kitchen hose and knocking off as many of the pests as a can.  Then I give the plant a thorough watering and spritz all the leaves and stems with a half-and-half (more or less) spray of rubbing alcohol and water mixture.  It's a home remedy I found online, which I figured I'd try before going out and buying some expensive (and potentially ineffective) pesticide.

I can't tell if this leaf damage is from the insects, or the alcohol sprays I've been applying, or if it's just a little weary from a hot and dry extended weekend when I wasn't home to water it as needed.  It was the only plant of mine to be particularly droopy when I returned home from Michigan this weekend.

With this most recent drenching and spritzing I ended up spraying out a lot of the soil, too.  I applied a topcoat of an African Violet potting mixture (the only fresh stuff I had), to cover up the roots that became exposed with the drenching.  I'm starting to wonder if reusing potting soil has its disadvantages.  I don't recall if I reused potting soil for this one, but I doubt I really shook it out when I transferred this pot from its store pot.