I, too, have battled these nasty little flying insects... and have tried lots of
stuff. The biological controls do significantly reduce the bug populations, but there
are a couple of other things that can help, too. I applied a little logic to a
statement that I read that said that the larvae live in the top layer of soil - and so
I changed the top layer of potting soil in my plants and found that it worked wonders.
(I have several hundred plants so it was no small matter.) I've also been told that
if you add a 1/2" of sand on the surface it will do much the same as the insects don't
seem to go through it.
Hope this helps some...
helge006 at gold.tc.umn.edu