I cannot get any Papilio species to feed.

Try feeding at different times of the day. They should sit and drink for several minutes.

If you are using wild caught butterflies, I have read that keeping them in the dark for a day

after capture will help them to adjust to captivity, I learned this after capturing Papilio rutulus

and they did not last long either, sounds similar to your problem.

Butterflies take a lot of room to pair naturally, I've only hand paired a couple Papilio species,

but they should stay coupled for at least an hour.

It's best to not put salt in with the nectar as it can cause them to dehydrate if they drink it all the time, you can try putting some in a small dish with a wet towel on the bottom of the enclosure. Do you use kitchen salt or rock salt, the butterflies prefer to have a mix of minerals, so it might be best to use Himalayan rock salt if you can get it easily, some supermarkets have it.

To get them feeding its best to have the feeder under a bright light preferably one which has UV and gives of a bit of heat, maybe a 30w-50w reptile basking light? they should feed for about 30 seconds to a minuet, 2 to 3 times a day, unfurl the proboscis and place it in the nectar you should see the end moving about if they are feeding. If they refuse to feed it might be best to change the concentration of the nectar, as if it is too dilute or too strong they refuse it as well.

I would think a wild butterfly should be able to survive well in captivity, but like I mentioned earlier,

after my experience with rutulus, I read that they'll acclimate better if kept in the dark for a day after

being captured.

I also think it's only males that need minerals, and perhaps females that are gravid, try gatorade with the

nectar.

You do have a large cage there, but it could probably use more light, think about how bright a sunny day is,

I use full spectrum led lights, they don't produce much, if any heat, and are bright, as well as inexpensive.

I bought my panel from eBay for about 25 bucks.

Hello,

Did you simply try to feed them with watered tree honey, lime's or chestnut's for example ?

With this kind of food P.machaon and I.podalirius live several weeks without any problem

For me it depends on the quality of honey used. Of course a cheap Chinese honey kill them in a few days, like basic sugared water. I did not see any problem like these you mention, even when I used already crystallized honey to feed them.

I have kept mourning cloaks during nearly a year feeder with honeyed water, so for me it is worth it.