While this showed the iridescent beetles may be more likely to survive bird predation, Kjernsmo and her colleagues believed the birds may still see the iridescent beetle cases, but avoid them on purpose, perhaps because they believe them to be venomous or otherwise unsuitable to eat.
So Kjernsmo and her colleagues conducted the same experiment, but this time with human volunteers who — presumably — had no desire to eat the beetles.
“If it’s explained that the birds were scared by the beetles, then humans should spot them easily,” she says.
But alas, “humans were surprisingly bad at spotting these iridescent models,” Kjernsmo says. They only spotted 17 percent of iridescent shells, compared to seeing 80 percent of the single-colored cases.
“It shows that iridescence is a very good strategy if you want to avoid being spotted,” she says, adding that this type of coloring probably works as camouflage in other species as well.