Scientists finally 'find' why flies are so hard to swat

Ever
wondered how the buzzing houseflies are so incredibly good at zipping
off to avoid even our best attempts to swat them? Well, scientists have
finally solved the mystery -- the insect's brain "senses" threat.

A team in the United States has found
that the fly's ability to dodge being hit is due to its fast-acting
brain and an ability to plan ahead -- in fact, it can work out where a
threat is coming from and prepare an escape route.

And, according to them, the best way of swatting a fly is to creep up slowly and aim ahead of its location.

"It is best to aim a bit forward of the
fly's starting position, to anticipate where it's going to jump when it
first sees your swatter," lead researcher Dr Michael Dickinson was
quoted by the 'Current Biology' journal as saying.

In their study, Dr Dickinson and
colleagues at the California Institute of Technology filmed an
experiment with some fruit flies and a looming swatter, using
high-resolution and high-speed imaging technology.

The researchers found that when the
flies saw an object hurtling towards them, they were able to plan and
carry out an emergency take-off in just under 200 milliseconds -- or a
fifth of a second.

And, a fraction of a second before the
flies sprung into the air, they managed to alter their body's position
so that they're properly prepared to jump in the right direction.

When the blow came from behind, the
flies moved their middle legs forward a little and leaned back so that
they were ideally positioned to jump forwards into the air and away
from the threat.

For a threat from the front, the
insects moved their legs backward and leaped that way. For sideways
threats, they kept their legs still and leaned to the other side to be
ready for a lateral escape, the researchers found.

In fact, the entire process of
calculating the direction of the threat and preparing the body took a
fly one tenth of a second and it flew away in two tenths of a second.

"We were surprised to find that long --
in fly time -- before a fly takes off in response to a predator or
swatter, it plans the direction of the jump by making a rather complex
series of postural movements.

"These movements are made very rapidly,
within about 200 milliseconds, but within that time the animal
determines where the threat is coming from and activates an appropriate
set of movements to position its legs and wings.

"This shows how rapidly the fly's brain
processes sensory information into an appropriate motor response. We've
also found that when the fly makes planning movements prior to
take-off, it takes into account its body position at the time it first
sees the threat.

"Our experiments showed that the fly
somehow 'knows' whether it needs to make large or small postural
changes to reach the correct pre-flight posture," Dickinson said.