In the home
In the farm or orchard
Again ants will only expend energy climbing onto trees, vines or other plants if there is some reward. To some extent this can be a ‘chicken and egg’ situation. Are the ants there because of the mealybugs or vice versa?
A variety of ant baits are available. The simplest of these is an old but well tested bait which incorporates borax as the toxicant. Small quantities of this relatively innocuous compound are taken back to the nest by an army of ant workers. It takes some time but eventually this action can reduce in size or kill out the colony. The important thing about an ant bait is that it should not be so toxic as to kill individual ants quickly before they have had a chance to return to the nest to transfer the toxicant to the colony at large.
A simple recipe for an ant bait is 3 cups of water + 1 cup of sugar with 4 teaspoons of borax. Some ant species prefer more or less sugar or may respond to protein (crushed dry dog food formula can work here).
Some commercial ant baits are available and these can be more or less effective. It is important to understand the habit of the ant species that is causing your problems before choosing your ant management strategy.
Because ants do not have wings (other than when swarming) we can exclude them if plants or other valued items are kept on elevated benches. The use of sticky barriers can be an effective tool. In this case it is important that there are not alternative access points that the ants can use. There are several sticky compounds available for this purpose. It may be necessary to re-work the material or apply a fresh band from time to time as dust and leaves can reduce the effectiveness of the barrier allowing ants across.