A reader wrote wondering whether anyone is investigating whether the monarch butterfly die-off in Mexico might relate to crops genetically engineered to contain the Bt gene for pest resistance. Rampton and Stauber, in their book Trust Us, We’re Experts, reported that more than 20 million US acres are planted with Bt crops, which are poisonous to many classes of insects. So I did a Google Search: “monarch butterfly” “Bt gene” “bacillus thuringiensis”, which comes up with legions of net references to concern about the lethality of Bt to monarchs in particular. Now, is Mexican agriculture into Bt? [thanks, Holden]