The highly publicized Cornell University study that reported that monarch butterflies died after ingesting pollen from Bt corn is being contradicted by prominent entomologists, including one from Cornell. The original study by John Losey, Cornell assistant professor of entomology, reported that pollen from Bt corn killed monarch butterfly larvae in laboratory tests.

Recently, Anthony Shelton of Cornell and Richard Roush of the University of Adelaide, Australia, reviewed the research and published their findings in Nature Biotechnology. The entomologists stated that Losey's research was flawed and did not resemble a situation in a real field. They compared the monarch deaths to a person dying after eating 100 lbs. of salted popcorn at one time.

The entomologists also expressed their surprise that a more reliable study done earlier at Iowa State University was overlooked. This study, conducted by Laura Hansen and John Obrychki, found that monarch larvae survived when fed milkweed with the highest levels of Bt pollen that would be encountered in the field.