•Muons are not larger than electrons, but they are more massive (10 July, p 10).
• Preying has nothing to do with it: the poster boy of risky sex is the male praying mantis (3 July, p 36).
• In our diagram of an optical illusion, the inner circles were not identical as claimed. In two of the four images, the pattern was horizontally displaced (10 July, p 28).
