Possibly thermal regulation? A too-cold butterfly that wants to warm up in the sun would want to increase exposed surface area. A warm-enough butterfly would

Possibly thermal regulation? A too-cold butterfly that wants to warm up in the sun would want to increase exposed surface area. A warm-enough butterfly would fold up those wings, as normal. A too-hot butterfly would slowly flap, preferably in the shade. I still can't internalize how butterflies can actually fly with those wings. It just seems like there would have to be so much twisting, curling, and flapping that they would either just flop around wildly in the air or rip their own wings off. But that's probably because I'm mentally trying to scale it up to Arthur-sized flight. Aerodynamics are a lot different when your whole craft is only a few grams. With the huge possibility that I'm wrong, I think a butterfly about to take off would want to extend its wingtips as vertical as possible, and lift off with a strong down-stroke, then twist parallel to the air stream and re-extend before twisting back to flap down again. Defensive is a strong possibility for butterflies with false eye spots on their wings, or zebra-stripe-like, outline-breaking herd camouflage.