Peter, I remember a reference to the subject in *The HIve and the Honeybee. *Also, I was just talking to someone on FaceBook about this 5 minutes ago, and I found this article, though I'm not a subscriber: http://www.jstor.org/discover/10.2307/4449292?uid=2&uid=4&sid=56059504813 Bill *********************************************** 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