When taking care of caterpillars using this method, it is advisable to remove frass (caterpillar poop) every other day and replace cuttings every 4-5 days or when the host has been consumed by caterpillars.  It is very common to stumble upon 100+ caterpillars at a time, with this particular species of butterfly.  When they grow into later instars, taking care of THAT many caterpillars can become labor intensive.  You may want to consider giving some to friends or returning unwanted caterpillars back to their habitat.