Here’s an interesting find from our malaise trap behind the Penn State Arboretum. This specimen is a phorid fly and likely belongs to the genus Lecanocerus. Take a look at those antennae!
What could these be used for? On top of obstructing sight directly in front of the fly, I doubt that these modifications make flight any easier. My guess is that these structures are a result of sexual selection, and play some role in courtship or mating. Male Drosophila fan their wings during courtship—do male Lecanocerus fan these structures as part of a courtship display? Or do males use these like horns to spar with each other for a chance to mate with a female? Is this some sort of sexual ornamentation? Do female Lecanocerus go wild for males with larger antennal structures?
I asked István for his opinion, and he thought that these might have a sensory function. The paddle-like structures might even hold glands inside. If these did secret some sort of gland product, such as pheromones, could the males move the structures to fan pheromones towards females?
What do you think?