If you are refering to the fungus gnat larvae, then these are
insects (maggots in this case) and not nematodes.
>They came out of the drainage holes of my D. capensis pot some
>time ago, and started swimming around in the water tray.
I haven't seen them do this, are we talking about the same
beasties?
>every morning when I turn the lights on, they turn their noses
>downward and head back into the soil.
This sounds like a fungus gnat, looks like a blowfy maggot only
smaller and more transparent. It also doesn't like light that
much.
>Could you be referring to the Root Knot Nematode? I couldn't
>find anything in my pest books about Nematode root worm, so I
>gathered you must be talking about the root knot.
Root-knot nematode : any of the species belonging to the genus
_Meloidogyne_. I dont think root-knot has ever been found on CP's
(no-one's probably looked :) ). This nematode has a very large
host range including vegetables (loves tomatoes and silver beet),
tobacco, grape vines and just about everything else. You can
discern the juvenile nematode with the naked eye, but you
wouldn't see them tucked away in the sphagnum. Also the adults
are sedentary on the roots and while quite large also cannot be
seen as they are in the plant tissue. What can be seen on the
roots is a large amount of knotting, resembling a callus. The
knotting is formed by the female nematode feeding.
>They suggest heating the soil to 125 degrees F for 30 minutes
>to destroy these pests and their eggs.
Solarization will also work, but I doubt seriously that this is
the pest that you are dealing with. The fungus gant is the most
likely culprit but there are also beetle, moth or butterfly
larvae that are similar.
There endeth the nematology lesson for today.
Cheers
Terry (who just happens to be a nematologist, come plant
pathologist)