well , i had a problem with small flies.....the bastards used the soil to breed and no matter how many i killed they multiplied....i solved the problem using a pesticide/insecticide manufactured by BAYER....it is called Confidor ...it exterminates a wide range of insects ,flying or not, and used for a wide range of type of plants....i.e tobacco,tomatoes,roses etc....it is extremely powerfull as it is diluted 1ml per lt of water....the population of the flies has been drastically reduced and the plants do not seem affected by the use of such chemical...their leaves continue to have dark green colours and growth is still going strong....the only backdraw is that it stinks like hell, but, i suppose it will go away after a watering or two.....
if you decide to use such chemical do not go into flowering before 10 days (and at least two waterings) have passed.....i have another 3 days to go into flowering myself...hope that helped.....