Vision model for the monarch butterfly, Danaus plexippus

Vision modelling of four effective photoreceptors of the monarch butterfly, Danaus plexippus, based on sensitivity peaks reported by Stalleicke et al. (2006) and Blackiston et al. (2011), and of a dark orange filter reported by Blackiston et al. (2011) and extrapolated from the spectrum presented for Heliconius erato in McCulloch et al. (2016). Relative proportions of photoreceptors are 1:1:3:3.