Though they may have similar heads and wing decoration, Signal Flies are their own thing, belonging to the family Platystomatidae (that’s a mouthful). The similarities will have to be noted and compared, but it must be acknowledged that the Signal Fly on showcase here is not a Picture-Wing Fly. I’m more inclined to believe the idea that the wings help attract mates (or possibly even serve to communicate other things) because we’ve seen similar behavior in the Peacock Fly, who holds its wings upright when roaming around its environment or when near others of its own kind. If they return to the backyard I’ll have to keep a close eye on them, watching for their metallic body and patterned wings.
Hmmm, maybe they’re flashing their wings to show off those patterns to attract other Flies, possibly mates. I could see the wings having use in temperature regulation, but generally wing motion is limited to be effective, and I’m not sure how much heat those stripes on the wings would absorb or radiate.
Flies by their design have halteres to balance themselves while in flight and have 6 legs to keep balanced when they walk. Why do they actually keep moving their wings as they move? I’m not entirely sure, but it can’t just be for balance. As they were crawling and searching on the leaves: their wings were always shifting around and orienting as if balancing. The pictures don’t really do their motions justice, as while it has been a few years since these pictures were taken, I can distinctly remember their most prominent behavior. The process continues to add more insect families to the blog, so today these tiny individuals will join the blog.