It achieves a slightly transgressive flavor, but it castrates itself a little with "Males." That single word fatally undermines the title, by weakening the impact of the overall phrase. "Males?" Who says that? Sounds like something space aliens would say, or robots. Now, of course it's alluding to the Praying Mantis, where the female often bites off the head of the hapless male during sex, which helps facilitate ejaculation, thereby perpetuating the species. Oh, sure, sure.
But two other titles scream out at me from the above phrase (and, of course, beyond the purview of the book itself, which is focused on the biology of sexual cannibalism)...
HEADLESS MEN MAKE GREAT LOVERS
Now, that title immediately makes me smile, makes me think "Huh?" It calls to mind all sorts of images, like what the hell the speaker of such a phrase could have in mind -- some kind of militant feminism? A dystopian future where men are fully reduced to their sexual function in the waning days of the sex (since we all know men-as-we-know-them are likely gone in another 150,000 years, at the rate the Y-chromosome keeps declining). Men who lose their heads make great lovers? Some psychotic radical romantic babe who beheads her lovers for whatever reason? All kinds of possibilities in that. And also...
HEEDLESS MEN MAKE GREAT LOVERS
This one almost qualifies as a sophistic manipulation (putting the MAN in MANipulation) of language, perhaps a retrosexual manifesto (haha -- MANifesto; it never stops, does it?) Something that attacks the Death Cab for Cutie school of Wussified Man(tm), seeks out the Natural Man(tm), tosses out Emo Man in favor of the Retrosexual Man's Man, who boldly goes where no man has gone before (or where other men have gone before, but not nearly so well). Perhaps an anti-intellectual screed praising ignorance as strength as the final solution in the war of the sexes. Again, such a phrase is pregnant with possiblities. This one would be strictly nonfiction -- it's a little more declarative than the other one, stakes out a kind of falsely assured tone inherent in those kinds of books. Whereas the first play on that title screams out for some kind of darkly comic horror novel -- a gleeful misandry right out of the starting gates.
It's fun to play with words.