Martin Brown writes

Easynews wrote:

I've tried all the bio remedies- parasitic flies of various species and
ladybirds. Now I'm facing millions of the greenflies- the air is thick and
they are swarming over everything, tomatoes, courgettes, cucumbers, herbs,
and fruit has pretty well stopped growing. I've been a committed organic
gardener for years- but this has got beyond a joke- any tips? It is a large
greenhouse- 18 feet by 10, full of plants.

If it is that far out of balance you are forced to fairly drastic
measures to regain control quickly. The fastest solution is an
insecticidal smoke knock down with low persistance - you can still buy
Permethrin based ones for amateur use as an insecticide. Afraid it will
kill every insect though good and bad alike. Smoke is very effective.
You could spray but getting under the leaves in a big greenhouse there
are always nooks and crannies you will miss.

Also you need to repeat after 7-10 days to get all the newly hatched
eggs.

If you really don't want to use pesticides, you could try something
which someone recommended in urg a couple of year back for whitefly, ie
a vacuum cleaner. I've just had a go on my whitefly and have been very
pleased. I used the soft furniture brush, and simply vacuumed the
underside of the leaves. Some of the plants look a bit wind-blown, but
no leaf damage that I can see, and a huge disappearance of whitefly.

It might not work with aphids, as I think they have a firmer hold on the
plant, but it could be worth a try.
--
Kay