Managed to work it out:
Had done the labels wrong:
dataRT$evolveto=factor(dataRT$evolveto, levels=c(0,1), labels=c("Camouflage", "Visible"))
Then call the ggplot functions like this:
bar3<-ggplot(dataRT, aes(gen,contrastT, fill=fiteval)) + stat_summary(fun = mean, geom ="bar", position="dodge") +stat_summary(fun.data =mean_cl_normal, geom ="errorbar", position = position_dodge(width=0.90), width =0.2) +labs(x="generation", y="Colour Disparity", fill="Evaluation Model") + facet_wrap(~ evolveto, labeller=label_value) + labs(title = "Evolve To")