So sorry! :(
It looks like what I call the "black death" - it's a virus, more common in monarchs than gulf frits.
It's not your fault, and there's nothing to do about it. Fortunately, it's not likely to happen again - it's only happened to mine once.
Sherry

How does it spread? I wondered if our passionflower was doing it.

Nah...more than likely a viral thing OR have you or your neighbors sprayed any pesticides or insecticides around lately? West Nile stuff, from the Vector Control, perhaps? How about fertilizer? Sometimes, when you fertilize your plants, a similar thing happens with the larvae. What's the temperature been like? Hot? Cold? Variable temps from morning to night? Day to day? There are a number of variables that could be causing this as well.

See if you can stop and think about what MAY be different right now. This may be difficult to do, yet, may hold the key to your problem.

In the meantime, chin up! This happens to ALL of us at one time or another. Don't give up. Things will turn around.

CalSherry aka tdogmom

I can't even bear to go look at my frillitary cats any more. I picked off three little ones, put them in a bug box with a few passionflower leaves, and watched them blacken/die too. So it's bacteria then? We don't use fertilizers (except for occasional Miracle Grow in the little garden) or pesticides. (Did I put some Miracle Grow at the base of the passionflower? Can't remember now.) Yes, it's been in the 90s here and sunshine hits the passionvine but not all of it.

I've thought of cutting back the passionflower because it's so ravaged and horrible looking. Everyone's dying that's hatched on it!

Sniff.

'So sorry, sherylsr!
If the virus can live on leaves or stems, then cutting it back would really be a good idea - 'don't know if it can, though. If it were me, I'd cut it all back just in case the virus can live outside the host.
Sherry

My cats are dying also! It is not a virus because I'm not keeping them on the passion vine. I keep the eggs I've collected, from the passion vine, in a butterfly enclosure. Could it be that the enclosure is too hot for them? Is there perhaps a virus in the enclosure where the first three died, still in there. Should I clean the enclosure? If so, what should I clean it with?

You should ALWAYS keep your enclosures clean. I remove my cages once or twice a season and put them - mesh and frame pieces - in the tub in hot water with about ?5% bleach added. It doesn't take much bleach to kill any virus. I rinse them several times, then put the mesh and frame in a place where they can dry. In addition, you should be removing paper towels with frass on them regularly (though not obsessively, like I used to do) and don't overcrowd your caterpillars. I've been raising gulf frits for years with no problems, so I think my methods must work. There are some tiny caterpillars on the vines outside, that I'll be raising in a few days.

Sherry

Misssherry: Would you mind sharing your method of raising Gulf Frits? I found one on my passionvine today, and would like to try to raise him in a mesh cage. Thanks... Beth

Hi Beth: I haven't raised Gulf frits in captivity. Sorry I can't offer any advice. Other than keep passionflower leaves with the caterpillar until it goes into its chrysalis.