butterflies are rather famous. They're colourful and beautiful
and migrate for thousands of miles between Mexico and Canada.
Experiments in 1999 showed that they were poisoned by GM Bt corn
pollen which had been sprinkled on milkweed leaves, their favourite
food. Later studies
showed that most of the Bt corn varieties seemed to be quite safe
for butterflies because they produced far less of the toxin than
the plants that had been used in the experiments. The highly toxic
variety which made up to 40 times more poison than others that
are available was taken off the market.
But it does
show that people have to keep checking for possible bad effects