What do Monarch butterfly caterpillars eat?
Caterpillars of the Monarch butterfly do not feed on corn plants – they eat the leaves of milkweed plants. The problem is that milkweed plants grow as weeds in or around corn crops, so when corn pollen is shed onto the leaves of milkweed plants, Monarch caterpillars eat the pollen as well. Non-GM corn pollen is usually not toxic to Monarch butterfly caterpillars, but the Bt insecticide is present in small amounts in the pollen of those GM corn varieties that contain Bt genes. A laboratory study has shown that if Monarch caterpillars eat enough insecticide-containing pollen from GM corn, they will be exposed to a sufficient quantity of insecticide so that they either die or they fail to thrive. The question is, does this happen in the field?
