Host plants:

Always have leaves of the host plant touching the sides or bottom of the rearing container. 

When larvae leave the plant to molt (or for other reasons) it will be easier for them to return to the plant to continue eating if it is touching the sides or bottom.  If they must play hide-n-seek, they’ll use precious energy seeking the plant, traveling in in circles, while looking for the plant.  The idea of going up the side of a pot or cup in the middle of the rearing container isn’t a natural instinct.