Butterfly
Kept as a life cycle rather than as a pet: egg, caterpillar, chrysalis, then a few weeks on the wing. The caterpillar stage is the one that needs the right plant.
Overview
A butterfly is not really kept, it is raised. You start with an egg or a caterpillar, and the animal spends almost all of its time with you as something that eats leaves. A painted lady, the usual first one, takes 33 to 44 days from egg to adult in warm conditions and up to 60 in cooler ones, then flies for 10 to 24 days.
The caterpillar stage is where the whole thing is won or lost, and it comes down to the plant. Caterpillars eat very specific plants, and the one you found it on is the one it eats. Painted lady caterpillars take thistle, mallow and nettle among more than a hundred recorded plants, but a caterpillar handed the wrong leaf does not compromise, it simply stops eating.
Temperament
Adults do two things: feed and look for a mate. They nectar from flat topped flowers, aster, clover and thistle among them, and painted ladies will also take the honeydew aphids leave on leaves. On a cool morning one will sit with its wings open to the light and do nothing at all until it warms up.
There is no bond here and no recognition, which is worth saying plainly before anybody buys one expecting otherwise. What you get is a few weeks of watching something fly in a room, and the knowledge that you fed it through everything that came before.
Care and grooming
Keep the foodplant fresh and keep it the same. Stems stand in a jar of water with the neck blocked with cotton wool, since a caterpillar that falls in drowns, and wilting leaves get swapped for fresh ones off the same plant. Rinse anything picked outside, and pick it away from roadsides.
Mist lightly once a day and no more than that. Heavy condensation on the walls kills caterpillars, which is the opposite of what most people assume about something that looks tropical. Do not lift caterpillars with bare fingers either: plenty of species carry hairs or secretions that irritate skin, and moving the stem moves the animal.
Living and exercise
Height matters more than width, and it matters most in the last week. A butterfly climbs and hangs to pump its wings out after it emerges, and if it cannot reach a clear spot the wings harden crumpled and it never flies properly. Twigs, stems and mesh sides give it somewhere to do that.
Once it is out, leave it alone until the wings are hard. That is the window where handling does permanent damage, and there is nothing to gain by interfering with it.
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