I am new to natural farming and agriculture in general, even though I am a follower of the permaculture movement for years, only this year started making garden in the backyard in just 180m2.
For now, what may be considered pests in my yard are large black ants that eat the geranium, broccoli, strawberries and gardenia, maybe something else, but they especially like that. I let them eat the geranium, patiently waited, they ate half of the geranium and it sprout again, then there was not a problem. They then attacked the broccoli, some that had been planted together in a groove, were almost completely extinguished, however those in other parts of the garden remained intact. They then attacked the gardenia jasminoides, have eaten half and seem to want to eat it all, so I had no choice but to throw rice and distracted them, as they say rice rots in the ant nest and bust them. The strawberries: were eaten all the leaves, but sprouted; anyway to make sure minimum strawberry production I had to put in plastic pots (they do not climb plastic), until I can discover how to balance the “plague” of black ants.
What could level them? Some animal? As all neighbors have yard, and I can not act in their yards, even when killed, the ants return again and again.
Another “plague” in my garden are snails, as we do not agree with my wife to introduce geese, ducks or other animal which devours snails and slugs, what little I can do is put crushed eggshells around basils for them to go, or at least cheat with glasses of beer sunk into the ground.
If I did not do any of this, the snails eat all basils.
Regarding the bugs that eat your beans, I read that Fukuoka recommends not planting in straight rows, as says the beetles usually eat in a straight line, but do not know how true is this for your situation.
As Ruth said, for natural farmers there should not be any “pests” at all, but I think we need to work and think a lot to achieve a reasonably successful cultivation without the bugs eating too many plants.
Argentina (pampa húmeda, min -3º C, max 39º C)