Allen asks <How do bees decide what pollen to collect? Do they not sense it and make a decision? > My own observations would indicate that they do. Desperate bees - when there is little or no available pollen and the colony has a need- may bring in substances like sawdust. But, if there's any choice, they seem to be choosy. All of our work says they've an exquisite olfactory system, in addition to taste and color recognition. My wife, who specializes in macro-photography reports bees discriminate 'fresh' blossoms for older - even if there is still pollen available. She watches and marks stems the day before a blossom is going to open - the bees head right for the newly opened flowers. We know bees are choosy about the nutritional value of nectar - lots of studies have been done. Its not hard to imagine that bees discriminate sweetness, much as we do. Humans can differentiate high concentrations of sugar from low. Not so sure we can discriminate the nutritional value of protein - a steak is different from a plate of beans, etc. But, we do have taste preferences - some of us prefer meat in our diet. That's a form of choice, not based on nutritional value. Who's to say bees don't have preferences? Finally, its not as readily evident as to how to set up a trial to see if bees can discriminate nutritional value of pollen as it is with nectar (where one simply adjusts the sugar concentration and/or type of sugar). Again, from our own work, given a choice, bees like sucrose better than high fructose sugar. Whereas some might argue that sucrose is a better diet nutritionally, its not obvious whether the bees prefer sucrose because its better nutritionally or just tastes better. Its probably not odor - unlike wasps, bees seem unable to locate sugar syrup based on odor alone. Jerry *********************************************** The BEE-L mailing list is powered by L-Soft's renowned LISTSERV(R) list management software. For more information, go to: http://www.lsoft.com/LISTSERV-powered.html Guidelines for posting to BEE-L can be found at: http://honeybeeworld.com/bee-l/guidelines.htm