In combat aviation, pilots have the option to fire decoy flares to get rid of a heat-seeking missile or similar weapon. It's interesting how butterflies essentially do the same thing. Of course, they don't literally fire flares, but a large part of their body is the flare. A predator may bite and peck at the wings, but they break off, and the insect escapes unscathed.
Here we see an Old World swallowtail (Papilio machaon, otakárek fenyklový) that's made good use of its flares. In fact, if you compare this with other photos, you will find this species has distinctive red and blue spots at the ends of its under wings, and in this individual they are completely gone, as is one of its "swallow tails". Clearly the butterfly's colours do a good job diverting the attention of predators to the peripheral parts of the wings.