Yes, I have noticed some butterflys can't hang on to anything for a long time after they hatch and the ones that have weak legs don't live very long. However, my little "Flutterby" is still here today 5 weeks and 3 days.
Once, I had one for 7 weeks and it was like a pet - as "Flutterby" is now. It is really hard when they die. But when you consider that most only live 3-4 weeks at the most, think these do extremely well.