Answer:
They starve to death.
Step-by-step explanation:
Bt maize is a species of maize that has been genetically modified to resist insect attack, especially in the larval state. This corn received genes from the bacteria Bacillus thuringiesis which has a toxic action for some insects.
That way, when the beetles eat the Bt maize leaf, they end up consuming these genes that are toxic to your body. These genes cause the formation of pores in the plasma membranes of cells in the larval midgut. These pores swell, turn into balls and explode causing a widespread infection that prevents the larva from feeding properly, causing it to starve.