Phil L wrote:
[...]
Upon closer inspection, they may be greenfly or aphids (I'm not too
well up on insect identification)
What brought my attention to them in the first place was hundreds
of
what I thought were dead ones on the compost underneath the
infected
leaves....I think these may be egg casings or similar but the
actual
insects themselves don't look white, they have a green tinge to
them.

[...]
have you tried the yellow sticky fly papers? And butterwort
(insectivorous plant) seem to like them.


I've not tried anything apart from marigolds...where do you get
that
yellow sticky stuff from? - what's it called?

Any decent garden centre should have them. Whitefly are now pretty
well pesticide-resistant (let that be a lesson to us!); but they love
yellow things. I've read that you can make your own by rolling tubes
of yellow paper or card, and winding sellotape, sticky side out,
round them.

Once you've identified whitefly there's no chance of mistake. They're
tiny little things looking exactly like doll's house moths, and --
surprise -- they're white. Greenfly are definitely green, and far
from elegantly moth-shaped: they have big bellies. You'll get more
whitefly on plants on the windowsill than greenfly, which generally
prefer the great outdoors. (But a friend claimed to have got greenfly
in his beer in an entertainingly low pub in Reading called The Jack
of Both Sides by sitting under a big roof light in which the landlord
grew his tomatoes. You don't have to believe it.)

--
Mike.