In each experiment, a single release of T. pretiosum was made at the equivalent rate of 250,000 females per hectare when 40% of corn plants reached the silking stage, followed by another release of 150,000 females per hectare five days later
The papers with parasitized eggs were glued to
the walls of 130 ml paper disposable drinking water cups
(Sweetheart Cup Company, Inc., Owings Mills, MD) to serve as
the standard release unit. Each cup was fastened with cord at the
base and suspended upside down on an individual corn plant to
prevent flooding of release cups. Six to eight such paper cups were
randomly placed in each release plot.