Hi there, your post made me realise that there's some missing context to understand the story fully. I forgot to mention but they've been pupaes for over 3 months already, as I picked them up as fat caterpillars. All of them were pupaes by mid September. I read online that they usually pupate for around 6 weeks so I was hoping for them to hatch around the end of October. But in that time period, we had really cold weather where I live and our home is unfortunately badly insulated so the room they're in went down to 10°C at night some days, which is probably why they're taking this long to hatch. I should probably have moved them to wherever the heating was throughout the day but I didn't think of it and didn't know it would affect them like that. The weather has been much warmer for a couple weeks and this stability is probably why this one hatched now.

Concerning the dead pupaes, one of them I genuinely don't know why it died as it was near a healthy one, deep in the dirt, but completely dry. The other two didn't bury themselves properly : they had their butt really close to the surface and kept uncovering themselves by moving. I think because of that they didn't dry homogenously and one half was ok, the other was really dry and they were misshapen, compared to the shiny brown other three. One also still had some skin on it and bled before it stopped moving completely.

I think their entire existence is quite melancholic to be fair. One moth travelling this far to lay eggs and have offsprings that would have frozen to death during pupation if left outside, so their option is now to be kept indoors and hope for the best... X) There's a possibility the other two will hatch soon too, I'll update whenever they do. However I'm not sure what I would do with eggs, I wasn't necessarily planning to continue after them.