I lost another caterpillar yesterday. Both the ones I've lost were from the 3 I brought in from the plants in front of my studio. The 3rd one seems to be thriving. Of course I was upset when I saw this 2nd casualty, so I inspected the plants to see if there were any doing OK out there. I found a dead one. Then, this morning, I found a live one (which I'm leaving where it is!). So, did a little research, and from the description I found of tachinid flies' effects on Monarchs, I'm thinking I might have brought some in. Fortunately, I keep each egg/caterpillar in a separate screen-covered container. Next year, I'll definitely be washing all the milkweed before I put it in with the cats.
Again, though, I let a beautiful female go today, and found 2 more chrysalises, so I'm down to 4 of those and one caterpillar.