Mosquito males and females beat their wings at different frequencies, but before mating they tune toward a shared harmonic. In *Aedes aegypti*, females (~400 Hz) and males (~600 Hz) converge near 1,200 Hz. A 2009 *Science* study found this synchrony is key to mate choice.
The animal that kills the most humans is the mosquito, causing 720,000–1 million deaths yearly through disease. The second deadliest species to humans is humans themselves, at roughly 430,000–475,000 killed by other humans annually.