use chlorpyrifos in a powdered kind, which does not work very effectively. You powder their entrances and contours, and hope for the perfect. I even get on fingers and knees and blow among the powder down the doorway. Inevitably in every week or so, they are going to be again, rinse and repeat for weeks on finish.
A organic agent would work higher.
Edit: Here is a pleasant article from Brazil the place scientists performed an experiment with some kind of processed orange pulp as a service bait into which they infused sulfluramid at 0.3% focus. Apparently the ants integrated extra of the sulfluramid pellets into their nest than even the management group (the processed orange pulp with none insecticide). Which may have simply been a coincidence, however the mechanism of motion sounds very convincing to me.
The sulfluramid may be very sluggish appearing, so the employee ants do not understand the compound. The ants feed this bait to their fungus and solely after the bait has been integrated into the fungus, does the sulfluramid begin to have an effect on the employee ants. The employees usually are not in a position to affiliate the bait as being the supply of toxicity as they can do with extra acute toxins from their surroundings. The article states that after three or 4 days the ants cease harvesting plant materials from the panorama, and all people die 16-22 days following the therapy.
Sounds promising to me. Now I simply must see if I can discover a product with this chemical composition.