Most insects have wings that appear to be transparent. Researchers from the University of Lund have found that they actually have rainbow colors, but the background of those wings makes all the difference in what the human eye sees.
“You hold the wing up against the light, so you can see the veins,” said study co-author Daniel Janzen, an evolutionary ecologist at the University of Pennsylvania. “If you’re looking through a microscope, you try to get a clear view behind the wing. It’s the antithesis of getting wing color.”
The researchers studied wings under microscopes, against black backgrounds. But once Janzen, who breeds wasps for his research on caterpillar-parasite symbioses, started to look, colors could be seen by the naked eye as wings passed over insects’ black bodies.
This study looked at the wings of wasps and flies, and the team believes they may find similar results in other orders of insects. Link