For the conduct of contact toxicity trials, Arkins and Johansen used C02 to put the bees to sleep. When this testing went to private labs, the protocol was changed by many to use nitrous oxide. That ignored older research that indicated that nitrous oxide induced a form of long-term amnesia in bees, whereas CO2 did not. Personally, I don't used nitrous oxide for that reason. 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