Just a little off the sides please…
Their spines are too small to cut off by hand. So the duo used a laser instead, wielding the light with such surgical precision that they could cut off a third of each millimetre-long spine, or the entire structure….
They found that a partial shave did nothing, but the full treatment significantly reduced the odds of the males mating with females.
The conclusion is that the fly’s penis hairs act as Velcro, to grasp the female long enough to inject sperm. Now you know.