&gt; One three-year study in Australia recorded cashew yields 49% higher in plots patrolled by ants compared with those protected by chemicals. Nut quality was higher too, so net income was 71% higher with ants than with chemicals.<p>With results like these, there must be some reason why this was not discovered and put to widespread use already. What are is down side? Containment? How to keep them from spreading to unwanted areas, like the farm house?