How can scientists see what’s happening on the inside of a pair of fornicating flies? One research team studying five species of tsetse flies used three techniques: (1) they flash-froze mating pairs, then dissected them; (2) they artificially stimulated males; and (3) they viewed copulating pairs with a new X-ray technique that allows events inside the female to be recorded in real time. The scientists admit that their data “almost certainly give only an incomplete view of this complex, previously hidden world.”
