CORBET: Welcome to the 6th of the SIO plenary seminars, which have been a feature of the SIO International Symposia since the one held in Chur, Switzerland in 1981. These seminars, or discussion sessions, offer a good opportunity for us to exchange information and views on various topics in odonatology, especially those topics which may be elucidated by the exposure of chance or anecdotal observations, because such observations are unlikely otherwise to be published or shared with a large group of odonatologists; also, of course, there is the great value of interaction among ourselves during these discussions which exploit the rare opportunity of our meeting in an enquiring frame of mind.