If you’re ever in Arizona, Butterfly Wonderland in Scottsdale is a must see. Prior to entering the massive butterfly pavilion, there’s a 3D film about the life cycle and migration of Monarchs.
For all the plants mentioned by others here, Monarchs can see them from very far away even if it’s a tiny patch in a sea of otherwise unfriendly territory. The most interesting thing to me was how the migration works across three generations, and the sizes of Monarchs are very different depending on the migration task ahead.
Start farming milkweeds. The monarchs will visit and you’ll have pretty distinctive larvae in no time. I guess in some places you can leave them outside and not suffer massive attrition.
We’ve got a ton of species of insect eating wasps, so we’ve got to take the little larvae inside ASAP.
