Here is a link about diatomaceous earth:
http://npic.orst.edu/factsheet...
Oftentimes, ants work in cahoots with other insects especially if they are able to source honey dew thru those other insects. So applying DE may solve another insect problem as well.
Since my collection of plants is not enormous, I can use it. So whatever methodology you use to control ants, it will depend on your time and patience. I really try to avoid strong pesticides of any sort, there are some beneficial insects that might be severely affected.
