Two-winged
insects characterized by active flight.
Flies are well adapted
for aerial movement, and typically have short and/or streamlined
bodies. The second segment of the thorax, which bears
the wings and contains the flight muscles, is greatly
enlarged, with the other two segments being reduced to
mere collar-like structures. The third segment bears the
halteres, which help to balance the insect during flight.
A further adaptation for flight is the reduction in number
of the neural ganglia, and concentration of nerve tissue
in the thorax, a feature that is most extreme in the highly
dervied Muscomorpha infraorder.
Flies have a mobile head with eyes, and, in most cases,
have large compound eyes on the sides of the head, with
three small ocelli on the top. The antennae take a variety
of forms, but are often short, to reduce drag while flying... |
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