Published online by Cambridge University Press: 10 July 2009
A technique is described for exposing insects to insecticidal deposits on detached foliage. Treated leaves are laid horizontally on boards with their petioles projecting through holes into water. Each insect is confined to the leaf surface by a small glass ring coated on its inner side with polytetrafluoroethylene and surrounded by a heavy metal ring to hold the leaf flat. This method is satisfactory for insects that do not spin webs and are unable to take off at a steep angle.