Comment on "Floral iridescence, produced by diffractive optics, acts as a cue for animal pollinators".

Whitney et al. (Reports, 2 January 2009, p. 130) investigated the mechanism of iridescence in hibiscus and tulip flowers and suggested that bumblebees are able to use this iridescence as a pollination cue. However, their study failed to isolate iridescence from other coincident visual cues, leaving open questions regarding the importance of iridescent stimuli in foraging-based associative learning in bumblebees.