Does pest-protected Bt corn harm monarch butterflies?
No. Bt crops incorporate genes from the common soil microbe Bacillus thuringiensis, which allows them to produce proteins (endotoxins) that protect them from certain insect pests. The protein expressed in Bt corn has long been known to be toxic to the caterpillars of butterflies, including the monarch. Laboratory studies confirming this led some outside the scientific community to claim that Bt corn posed a severe threat to the monarch.
