Q.What’s Eating My Milkweed?
Please help! I am so upset about my garden. I grow swamp milkweed and lots of Missouri native plants for pollinators. For years, my family has welcomed monarchs, protected the larvae, and released the new monarchs! Last year, a pest started eating my milkweed. I cannot see any bug, and it seems like the stalks are being eaten from the inside. Everyday, new stalks/branches are cut off the plant and I find them on the ground. It has already started happening this year to my brand new monarch stalks that are only a few inches tall! Plus, the same thing is now happening to my false indigo plant. How do I stop this from happening and also not ruin the milkweed for the monarchs! Please help!

Certified GKH Gardening Expert
Unfortunately, your photos did not come through. I am unable to see any potential damage. Since there isn't any visible signs of the culprit, you may have a hard time treating the issue.
There is a possibility that there are monarch larva that have managed to hide within the plants. Likely, you would see signs, though. Careful maintenance will ensure that you don't have any runners. That would not explain the false indigo, though.
There is a possibility that you have an outside species that has made its way into your crop. Again, careful inspection will help, as well as disrupting the lifecycle.
If the case is borers or wasps, then predatory control will help.
https://www.gardeningknowhow.com/plant-problems/pests/insects/beneficial-insects.htm
It is worth noting that there are certain predatory insects to stay away from, including paper wasps, ants, and certain species of parasitic wasps in the family Braconidae and Ichneumonidae, specifically, however.