2

N. Chari and P. Srinivas

Figure. 1.1 Morphology of a typical insect (Adapted from various sources)

such, the mechanism of insect flight is not fully understood even to this day. The wing

movement is quite prominently of flapping type and highly complex. The ability to

fly has played a major role in their worldwide distribution, biological survival, migra-

tion and navigation of these fliers. Numerically insects form nearly three-quarters of

a million (750,000) living species and form a major essential link in the life chain

of biological systems [1]. A deep understanding of insect flight offers a very good

example of morpho-functional correlation needed for understanding the biomechan-

ical design of MAVs as well as the associated features of the flapping flexible wings.

Insects are distributed all over the world. The evolution of insect flight as a marvel

of nature remains to be elucidated fully Fig. 1.1.

General Characters

Morphological Features

(1)

Flying insects have a streamlined body with a distinct head, thorax and

abdomen, and for improved flight capability, a pair of wings offering less

drag.

(2)

The head has mouth and associated mouthparts, compound eyes and a single

pair of sensory antennae. The mouthparts usually are of biting, chewing,

suckingandpiercingtype.Theheadisformedduetothefusionofsixsegments

during development.

(3)

Each compound eye that gives a mosaic image has many functional single

units known as ommatidia. The number of ommatidia varies in different fliers.

The dragonfly has 10,000 ommatidia.

(4)

Ocelli are small simple eyes having a lens and a retina found on the top of the

head between larger compound eyes. Compound eyes can sense ‘optic flow’