Page 40 - Design in Nature

The housefly uses the labellum in its
mouthpart to "quality test" food before
feeding. Unlike many creatures, flies
digest their food externally. It applies a
solvent fluid to the food. This fluid
dissolves the food into a liquid that the
fly can suck. Then, the fly takes the
liquid nutrients into itself by means of
the labella which gently dabs liquids
into its proboscis.
A fly can easily walk on the
most slippery surfaces or
stand still on a ceiling for
hours. Its feet are better
equipped to hold on to
glass, walls and ceilings
than those of a climber. If
the retractable claws are not
enough, suction pads on its
feet attach it to the surface.
The holding strength of the
suction has been increased
with a specially applied
fluid.

The flight of a housefly is an extremely complex phenomenon. First, the fly
meticulously inspects the organs to be used in navigation. Then, it takes position
ready for flight by adjusting the balancing organs in front. Lastly, it calculates the
angle of take-off, dependent on wind direction and velocity, by means of the sensors
on its antennae. Then it takes flight. But, all of these happen within one hundredth
of a second. Once airborne, it can accelerate rapidly and reach a speed of 6 mph (10
km/h).
For this reason, we could well use the nickname "master of acrobatic flight" for
it. It can fly in extraordinary zigzags through the air. It can take off vertically from
where it stands. No matter how slippery or uninviting the surface, it can land
successfully anywhere.
Another feature of this magical master of flight is its ability to land on ceilings.
Because of gravity it shouldn't hold on but fall down. However, it has been created
with certain systems to render the impossible possible. At the tip of its legs, there are
minute suction pads. In addition, these pads exude a sticky fluid when in touch with
a surface. This sticky fluid enables it to remain attached to a ceiling. While
approaching ceiling, it stretches its legs forward and as soon as it senses the touch of
a ceiling it flips around and takes hold of the ceiling's surface. The housefly has two
wings. These wings, that are halfway merged in the body and are comprised of a
very thin membrane intersected by veins, can be operated independently from one
another. However, while in flight they move back and forth on one axis just as in
single-winged planes. The muscles enabling movement of the wings contract at
take-off and relax on landing. Although controlled by nerves at the beginning of