Are Ants a natural bug/pest controller? LadyBugs?

I read somewhere that it was good to put Ant food around the outskirts of your plants to regulate bugs and pests around your plants.

Ive also heard that ants can ruin roots by making a nest in the ground and munching on the roots.

If I'm just putting down some food though shouldn't that just attract ants from their own nest creating a natural fence of ants? Presumably controlling bug problems?

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Ive also heard dousing your plant with ladybugs helps with bug problems. Is that true

How do you douse a plant with ladybugs? That is a new term to me but ladybugs are a beneficial insect. Good Luck dirrtyd