Share 'Should I give up on my lettuces?'

There seem to be aphids? (little green bugs, flying gnats and white egg like things) on my lettuce plants - I think it might be aphids in various stages of lifecycle? I've sprayed with a combo of garlic, mineral oil and water - which has the effect of making the whole garden smell of garlic but doesn't seem to be elimnating them. I can't find ladybugs in the city, I think they'd do the trick ...