The side of the head is about the only place that insects do not have ears. The closest that insect “ears” get to the head are the ears of mosquitoes, located at the base of their antennae. Known as Johnston’s organs, these bulbous structures are sensitive to the vibrations of the antennae. The antennae of mosquitoes are most sensitive to the sounds made by beating wings of other mosquitoes.
The mosquito species that transmits yellow fever, Aedes aegypti, has been extensively studied in order to find better ways to prevent yellow fever. Male Aedes aegypti will orient to the sound that the wings of a flying female mosquito makes. The heavier female beats her wings at about 400 beats per second (Hertz). The male beats his wings at a slightly faster 600 Hertz. In musical terms, the female sings a “G” and the male sings “D”.
Musicians will know that D is the fifth note of the G major scale. As the male mosquito approaches the female, it adjusts its wing beat frequency slightly so that it forms a “perfect fifth” with the female wingbeat. The interaction of the male and female wingbeat sounds creates a harmonizing “overtone” at 1200 Hertz. The perfect harmony is a signal that the male and female mosquito are right for each other and mating will proceed.
Recordings by Cornell biologist, Ron Hoy and other in his lab, confirm that Johnston’s organ is sensitive to sounds up to 2000, Hz. This confirms that the harmonic is well within range of mosquito hearing. Although humans find the buzz of the female mosquito annoying, mosquitoes in love can “sing” in perfect harmony.