text: depends what you want to train them on. Can be 10 days or 10 sec. Depends also how high of a percentage of recall you want, for how long you want them to remember as well as on the effectiveness of your reward. If you give them yummy enough sugar water bees can with one trial associate an odor with the reward. \nLook up training of honey bees (proboscis extension reflex) and training of fruit flies in simple mazes. \nAlso look up learning and memory in the sea slug Aplysia,  our understanding of molecular mechanism of learning and memory is based on experiments done with that invertebrate