This is a photo of the rare Two-Headed Silver-Spotted Butterfly. It is a non-migratory species, because it can never agree which direction to fly.
I made that up.
This is actually a photo of two Gulf Fritillary Butterflies, in the middle of mating. I spotted them a couple of days ago on a tomato plant. The Gulf Fritillary is fairly common in the Desert Garden, and one of the handsomest of butterflies. We most often see the pale spotted undersides of the wings, as pictured here, but the top sides are a rich bright orange (see below).
The Gulf Fritillary is an example of very specific adaptation; its larvae (caterpillars) eat only the leaves of members of the Passion Flower genus (Passiflora). If you grow a Passion Flower vine in your garden, you can be certain that the Gulf Fritillary will find it and the caterpillars will eat it nearly to the ground. Not being a great fan of Passionfruit, I don't consider that such a bad thing. If you're keen to have Passionfruit from your garden, try this: plant several Passion Flower vines, and treat one or two of them with BT (Bacillus thuringiensis) when you first spot the butterflies fluttering around, and subsequently, as needed, carefully following the label directions. Leave a few of the vines untreated and let the caterpillars have at it. As the adult butterfly visits many different flowers, it's worth viewing this insect as beneficial.
As a side note, this butterfly's larval food, the Passion Flower, derives its common and botanical names not from any aphrodisiacal powers, as is sometimes assumed, but from the Passion of Christ. The various parts of the vine and its flower's elaborate structure are taken to symbolize the Crown of Thorns, the three nails and five wounds, the lashing, the Centurion's spear, et cetera.
Plants are very interesting.