Thanks so much to BugGuide for the ID help. I sent in a request and got an answer in less than a day.
Killer Butterflies, Beware
If you think a tiny butterfly fluttering around wild flowers is the very picture of sweetness and light, let me tear that illusion in two now and forever. BZZZPHT! This bad boy is no vegan hippy.
When Ceraunus butterflies are caterpillars, looking a bit like slugs if I may say so, they will sometimes establish false relationships with ants. Like aphids, they will exude a sugar to attract ants who then protect the caterpillars from predators.
Unlike aphids, these caterpillars won’t allow themselves to be exploited or farmed. Should any ant get too bothersome, the caterpillar will EAT him.
The pictures above are of a male Ceraunus Blue butterfly. The word ceraunus comes from a Greek word for thunderbolt. The male’s wings really did flash an electric blue on flight. The female’s wings are a kind of stormy blue-grey.
This was the tiniest butterfly I have ever seen: about the size of a fingernail. They seemed to fly frantically — nearly non stop — otherwise I am sure I would have overlooked them.
I do. even if they are killers. They live in Texas, Florida and places further south. I saw several this week in a field of little bluestem, asters and one unknown (to me) tiny pink flower that seemed to occupy their attention. I want that flower in my garden. Their official host plants seem to be mostly legumes: partridge pea, rosary pea, bundleflower, clovers and indigofera.
I kind of get the impression these are far from rare. They can produce multiple generations in one year so I bet someone out there considers them a pest.
Not me. Coincidentally, I planted some indigofera last weekend and I’ve got some bundleflower seeds in the fridge. If I am lucky maybe I’ll see some tiny blue killer butterflies fluttering around my garden next year.