We use Dimilin G (4% diflubenzuron) from Maag AG to fight the small dipteran black flies (Trauermücken). It is a granular substance and sprinkled onto the soil when the plants show the first few rosette leaves.
In addition we use Neocid Total. It is a regular spray containing permethrin (0.3%) and tetramethrin (0.15%). Spray it from some distance onto plants or walls, shelfs etc. It is an all-purpose killer (beetles, mites, ants, flies...) and kills the adult black flies quite efficiently.
We also use Solbac from Biocontrol AG to fight black flies. It is based on Bacillus thuringiensis ssp. israelensis.
use 2.5 ml Solbac per 2-3 l of water (weak infection)
use 5.0 ml Solbac per 2-3 l of water (strong infection)
However, the best way to keep the black flies low is to move old plants, kept for harvesting seeds, to another place.
Against thrips we found that Amblyseius cucumeris, a mite, seems to work quite OK, at least if the thrips population is very small. They come in bags that you put up between the racks. We get them also from Biocontrol AG.