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adaptation for dispersal mechanisms. Some biological fliers such as insects, birds and

bats migrate depending on pronounced flight activity in search of food, sexual activity

(breeding grounds) and as an adaptation for favorable environmental conditions.

Migration can broadly be classified as short distance and long distance, depending

uponthespeciesflyingcapability.Duringmigration,theflierneedscontinuoussupply

of energy (fuel). The flier needs proper orientation by making use of its sensory

feedback systems which are extremely complex and subsequently it has to orient

and fly in the direction of its destination.

Insect Migration

Insect migration is characterized by relatively low mass, body offering less drag,

chitinous membranous wings on thorax, high frequency of wing beat and extremely

well developed unique sense organs for navigation different from homeotherms.

Insects are equipped with well developed mouth parts, compound eyes, ocelli (simple

eyes) and a pair of sensory antennae, sensory hair with innervations at the base known

as trichobothria which are present on body and wings. They help in detecting wind

flow. The migrating insects possess better and efficient aerodynamic features, well

developed powerful aerobic flight muscles and an elastic rubber like substance known

as resilin at the wing base. The resilin and wing get coupled and contribute for low

and high frequency wing movements in neurogenic and myogenic fliers and for the

development of aerodynamic forces due to beating of flapping flexible wings. The

migration is possible due to reaction between sensory organs and various navigation

factors which is not fully understood. Many insects migrate in swarms. The best

example of migrating insects are migratory locust and American monarch butterfly

which migrate a distance of more than 4000 km. In many cases return migration

(home coming) is done by subsequent generation of fliers as in the case of locusts

and Monarch butterfly. On the other hand return migration in homeotherms, same

flier flies along with young ones.

Migratory insects cover a distance ranging from a few kilometres to some thou-

sands of kilometres based on different atmospheric weather and geographic condi-

tions [1]. Desert locust Schistocerca gregaria recorded to be having the longest

migration is mostly found in Caribbean islands and at some regions of Panama

Canal, Africa, Middle East, Arabia and India. They flew in some kinds of trop-

ical wave patterns for a distance of 4,500 km [2]. Swarms of Schistocerca involve

about 1,000,000,000 locusts. The swarms cover a distance of 30–40 km per day. The

swarms are also called as startiform and cumuliform swarms [3]. The migration of

S.gregaria from Africa to India and also remigration has been shown in Fig. 10.1.

The directed long migration in locusts is controlled by winds, and it is tenacious.

Many entomologists and scientists have noted that most of the insects do migrate at

high altitudes by using fast flowing airstreams to travel long distances. Wind streams

influence insect flight strongly during migration [1]. Strong uni-modal distribution of