No action at all unless you can find a plant that's been damaged by them - until you do, you don't know where they are. They prefer plants in pots, but also can occur in the ground around shrubs - if you see notched holes on leaf edges, then you'll know there's a problem.

Have you checked carefully? There are other weevils that look similar.

no you can find them most times if it is mild enough. Just crush them.
I found an adult lily beetle on Wednesday crawling up the dead stem of a martagon lily. it clearly emerged from the soil. it is now dead.