Developing corn ears were sampled from all treatment plots three times at five-day intervals during the corn silking stage.
The first two samplings of corn ears were timed a day after the first
and second release of T. pretiosum in the release plot,
respectively and then again five days after the second release.
On each sampling date, 40 ears were randomly sampled from each plot and brought to the laboratory to isolate H. zea eggs from the corn silks.
Each isolated H. zea egg was encapsulated in a gel cap and observed for emergence of either a H. zea larva or parasitoid.
Observations on the number of eggs, and emergence of larvae or parasitoids were recorded to calculate percentage parasitism and proportions of eggs that emerged to yield either larvae or parasitoids.
Additionally, each corn ear was beaten by hand 30–40 times to dislodge thrips and Orius spp. on a clean surface for capture and quantification.