We followed the white caterpillar and managed to keep track of it during the butterfly stage, sort of.  We did know which chrysalis it was in.  So we immediately released all butterflies that emerged in the first few days.  Once that butterfly emerged, we kept all the butterflies from that day for mating.

It was difficult, if not impossible to identify which butterfly came out of that chrysalis.  At the butterfly stage, we couldn't find any sort of marker that identified the butterfly that had been a white caterpillar.  But since we kept all the butterflies from that day, it was likely that that butterfly would be part of the group that mated.  My son wanted to know if the trait that made some butterflies white was genetic, so of like eye color in humans.

The first batch of butterflies mated, and laid eggs.  We watched those eggs hatch and followed a new set of caterpillars.  There did seem to be more white caterpillars and even black caterpillars with white fur in this group.  

My son decided to take this experiment one step further.  There were two really white caterpillars in the group we were raising.  He wanted to find out what would happen if they mated.  So we kept them separate from the black caterpillars once they were close to the chrysalis stage.  

Now, they have emerged from the chrysalis stage and still look like all the other painted lady butterflies we have raised.   I can't see any distinctive features at this stage. 

It looks like there might be a male and female butterfly.  Over the next few days we'll find out if they are successful at mating.  It will be interesting to find out if their eggs turn into white or black caterpillars.