This Cabbage White butterfly looks like she’s been in some battles. The right wing has chewed-up edges and the left wing looks like it could use some major patching. Still, moments after I took this picture, a male approached her, and they went off dancing their aerial duet into the distance. Cabbage White males likely don’t care about beat-up wings. They probably don’t even see the damage. To their eyes what matters is the female’s ultraviolet blue color. We dull-eyed humans can’t see it, but the butterflies can see ultraviolet colors vividly. The female also doesn’t see the male as white, she sees him as purple. They probably see a lot of other things we don’t see; they live in an alternate visual universe. Not only visual, but also chemical. These bugs spray pheromones in the air around them to signal whether they’re interested in hooking up. That’s perfume that comes from their bodies, not stuff that’s sprayed on.
Here this Cabbage White is nectaring on some of the last of the blooming Wild Radish (Raphanus raphanistrum). People who study this butterfly say that its favorite weedy plant is Wild Mustard (Hirschfeldia incana) , which is flowering in great abundance in the park at this season.
Some of the best documentary nature writing I’ve ever read is an article on this butterfly in the summer 2018 issue of Bay Nature by Kaitlin Kraybill-Voth. She achieves the Holy Grail of science writing, or maybe all realistic writing, by unfolding a rich, complex, many-dimensioned world hidden in this most common of all fluttering bugs. The poet William Blake called this the power
To see a World in a Grain of Sand
And a Heaven in a Wild Flower
Hold Infinity in the palm of your hand
And Eternity in an hour
Well, you’ll have to go read it. There’s other good work about this butterfly as well. Its sex life is now a matter of wide scientific understanding, although not without gaps. We know, for instance, that the female exercises choice in mating and indicates lack of consent by arching her body. Source. There is much more as well.
All of this scientific interest arises, you guessed it, because this butterfly, or rather its caterpillars, ravenously devours crops in the cabbage family (Brassicaceae), which includes cabbage, kale, bok choy, broccoli, Brussel sprouts, collards, radish, turnip, kohlrabi, and many others. Your kid who hates vegetables may wish this butterfly well. Farmers who raise these crops definitely do not.