In reply to Sara's enquiry as to gnat eating CP's ...
Wayne's reply answered many points but I thought I'd just add that
Pinguicula moranensis has a long history of being the plant (I mean THE
PLANT) that orchid growers have used to keep down small flies that could
endanger the orchids.
There are many versions of P. moranensis, many incorrectly named or
using names invalid for many years now, but that shouldn't stop you
using the plants. Anything calling itself a variety of P. moranensis
(any variety) or possibly using names like "P. caudata" or "P.
mexicana" are good. As hybrids tend to be more vigorous you could also
use any hybrid of tender species (e.g. P. x kewensis, P. x 'Tina', P. x
'Weser'). In america this probably means any hybrid as I doubt there
are many, if any, hybrids of hardy species available through commercial
outlets. (I'm sure someone will correct me if I'm wrong).
Going back to Wayne's reply, you'll never trap all the gnats using CP's.
But if you keep them poorly, you'll actually increase the gnat
population (but I'm sure the gnats will be grateful). Try to ensure
that while in growth, the Pinguiculas (or other CP's) cover as much of
the soil as possible and that little or no plant material remains
rotting on exposed soil. I suggest that you even consider covering
exposed soil in a layer of neutral rock, the best being granulated (or
even pulverised) volcanic rock (very sharp, very dry to touch but it
actually retains and absorbs water). Any exposed soil will attract gnat
egg laying if there is any rotting vegetation available as a food
supply.
Regards
Paul