I heard recently that caffeine has insecticidal properties. I have no idea
yet whether there is any truth in this. The aphids haven't got going yet in
UK but somebody in a more favoured climate may like to make a brew of tea and
when it is cold apply it to half of a plant attacked by aphids, leaving the
other half untreated as a control. It would be appreciated if they could
report back with results if any.
Sorry this isn't directly about bees but the less noxious chemicals sprayed
on plants the better it is for the bees and for us.
Chris Slade