Certain genetically modified strains of maize produce a powerful natural insecticide  The insecticide occurs throughout the plant, including its pollen  Maize pollen is dispersed by the wind and frequently blows onto milkweed plants that grow near maize fields  Caterpillars of monarch butterflies feed exclusively on milkweed leaves  When these caterpillars are fed milkweed leaves dusted with pollen from modified maize plants, they die
Ttherefore, by using genetically modified maize, farmers put monarch butterflies at risk
Whether insects that feed on genetically modified maize plants are likely to be killed by insecticide from the plant's pollen