Scientists discover mosquitoes' stealth secrets

Stealthy mosquitoes have evolved a sneaky mechanism to avoid being detected when taking off from their prey, scientists have discovered.

Unlike other insects, which push off from their landing surface and then start furiously beating their wings to take flight, mosquitoes minimise the force felt by their prey.

"Mosquitoes take off mostly with their wings and push off with their legs very, very lightly, or maybe not at all," said Sofia Chang, a University of California, Berkeley graduate student who studied malarial mosquitoes.

"If they were to push off a lot more with their legs, they wouldn't have to produce as much lift with their wings. But if they lift just with their wings, you won't feel them coming off your skin."

Working at the Florian Muijres laboratory at Wageningen University in the Netherlands, Ms Chang used high-speed cameras to film mosquito take-offs - shooting at 125,000 frames per second.

The team used sterile specimens of a malaria-carrying species of mosquito and hoped to find clues about how to defeat the insects in their flight manoeuvres.

"These studies may also give tips about how to build very, very small robots. That is a field where miniaturisation is a Holy Grail," said Ms Chang.

Alongside UC Berkeley's integrative biology professors Robert Dudley and Mimi Koehl, Ms Chang found mosquitoes began to beat their wings 30 milliseconds before lift-off.

The insects' extraordinarily high wing-beat frequency of about 600 beats per second contributes to their extremely annoying whine, and is three times faster than the wing beat speeds of similar-sized insects.

The team found that fruit flies exerted almost four times the force of mosquitoes when they pushed off during take-off.

They are planning to study mosquito landings next, which are equally stealthy.