Corrections and clarifications.
The Random Samples item "The mosquito and the marigold" (12 May, p. 809) incorrectly suggested that a team of scientists in India first characterized phototoxins in marigolds that kill mosquito larvae. In fact, they were originally discovered in the early 1980s in Canada by investigators at the University of British Columbia [see J. T. Arnason, B. J. R. PhilogAne, P. Morand, K. Imrie, B. Hasspieler, A. E. R. Downe, "Naturally occurring and synthetic thiophenes as insecticides," American Chemical Society Symposium Series 387, 164 (1989)].