“Bt corn risk to monarchs is ‘negligible'” is full of manipulative words. How exactly was the “highly polarized atmosphere surrounding genetically modified crops . . . hampering attempts to rationally plan and evaluate research”? The companies that make the strains of corn discussed in the article are not named, of course. Nor are any ties between researchers and these companies specifically confirmed or denied. The article characterizes another researcher’s counter opinion as “grumbles.” The “strong polarities that cloud research on monarchs” are not named, except the public concern (“alarm”) that supposedly “fueled” the government’s involvement in the first place. Valerie DelMedico
Columbus, Ohio

As a lepidopterist for over 40 years, I found the discussion about Bt corn and monarch populations ludicrous. If monarch-overwintering habitat in Mexico disappears, as seems all too likely, the only U.S. population will be west of the Rocky Mountains, well away from the corn belt and further exposure to Bt corn pollen. If only a portion of the effort and money spent to prove the safety of Bt corn to monarchs were expended helping Mexico save monarchs’ winter habitat, we’d be dealing with a really important issue. Milton T. Taylor
Clemson University
Pendleton, S.C.

Tom Turpin of Purdue is right to remark that Bt corn’s effect on monarch butterflies obscures wider issues. Once we release genetically modified organisms, we may never be able to recall them. As Turpin notes, we don’t know the long-term effects of Bt toxin on soil organisms. There has been only the barest investigation of the effects of Bt corn in animal feeds, let alone in the human food chain. The monarch question, while worth consideration, pales in comparison with these issues. Hugh M.S. Lovel
Blairsville, Ga.