In laboratory experiments scientists have found that the pollen from Bt corn is lethal to monarch butterflies. Monarchs don’t eat corn pollen, but they do eat, exclusively, the leaves of milkweed (Asclepias syriaca), a weed that is common in American cornfields. When monarch caterpillars eat milkweed leaves dusted with Bt corn pollen, they sicken and die. Will this happen in the field? And how serious will the problem be if it does? We don’t know.
