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Due to the difficulty of visual information at night, these migrating insects exhibit

random patterns of flight headings to follow the downwind [4, 5].

Navigation—A General Overview

A sense of navigation and orientation is needed for the migratory insects to identify

the wind-speeds and directions so as to make a suitable correction in their flight

schedules. They use sun for orientation during daytime based on the movement

of sun. Some of the butterfly takes demonstrated endogenous time compensation

mechanisms when they were kept in darkness.

The insects are capable of sensing polarized light in cloudy sky as in birds. Some

researchers also reported that the migratory butterflies also use earth’s magnetic fields

by sensing the magnetic particles [22].

The wind-speed and its direction also influence the migration. Some of the insects

make use of the wind-speed for their migration by flying to high altitudes. They reach

to certain levels of heights and flow with the help of prevailing winds.

It has been reported that birds use the visual land marks, star patterns, sun as a

compass, moon orientation, meteorological conditions, geomagnetic fields, polar-

ized light, infrared, olfactory sense, mental maps, visual and sound vibrations and

gravity. The integration of all these features during migration in insects remain to be

elucidated fully [23] (Table 10.2).

Summary

The study of insect migration helps us to understand different scenarios and mecha-

nisms involved with low body mass, low Re and fliers travelling with low velocity.

The physics involved with low Re and low velocity is still to be explained. The role

of insect antennae and sensory hairs (Tricobothria) for pressure detection and feed-

back system remain to be elucidated fully. The aerosol problem and wind gusts may

interfere with small biological fliers. These ideas are to be considered carefully while

designing low speed man made fliers like MAVs. Long distance migrating insect body

and derived flight parameters may form the basis for MAV body and wing design. In

the MAV design it is possible to make use of bio-mimicking principles from small

biological fliers. Any bio-mimicry at the level of flying organism, or wings, or phys-

iological principles or at the molecular level contributes to bio-mimicking. In the

present state of knowledge it is not possible to use and incorporate the body and

flight parameters directly since it involves a careful scaling and design of nano-aerial

vehicles, which are primitive as for experimental designs are concerned.

The interrelationships of various types of migrations including diapauses and

environmental conditions are beyond the scope of present article.

Examples of some migratory insects [7, 24].