In article , ajr
writes
Evening,

I think that this topic was covered about a month ago on this group but I
can't find it on my system - so apologies for repeating the question.

My tomatoes are still growing/ripening etc, however the leaves on the plants
are covered with little white flies - little negatives of black flies!

What are they, what do they do and should I do something about them next
year or leave them alone?

Assuming that the tomatoes are growing in a greenhouse, it would be well
to tackle them now while they are active or they will hibernate over
winter to re-breed and become an annual nuisance to all your crops. They
are there because they like the conditions, so you will need to make
things less pleasant for them, while at the same time not harming your
plants or their crops.

We use an infusion of nettles in water for that job because it is an
organic insect repellent rather than a chemical pesticide which can
leave unwanted residues on the tomatoes. We apply it to the leaves of
the plants and within a day or so, all the white flies are gone. Any
remaining nettle infusion is then ingested through the leaves into the
plants to act as an organic plant tonic and feed.

Nettle infusion can be prepared by soaking young leaves in water for
7-10 days, by which time they will have biodegraded. The infusion has a
characteristic odour, but it is not long lasting and is one of the
reasons for its effectiveness. Full details can be read in the urg FAQ
on the subject at: http://www.nugget.demon.co.uk/MetaFAQ/nettle.html
--
Alan & Joan Gould - North Lincs.