This document discusses insect migration in three paragraphs or less: Insects migrate to escape unfavorable conditions like temperature extremes, lack of food or water, or overcrowding. Common migratory insects include monarch butterflies, dragonflies, locusts, and aphids. Migration can occur over long distances of hundreds to thousands of kilometers and is often driven by seasonal changes and availability of resources across environments. Remote sensing technologies like radar are useful for monitoring large-scale insect migrations.

1. Migratio
n in
insects
Praveen Kumar
CCSHAU,
HISAR

2.  Involves displacement of entire populations
 Displacement from breeding, feeding and
overwintering sites
 Individuals displaced hundreds of kilometers
 Regular feature of seasonal cycle for some insects
 The word "migration" is referred to movements of
animals in a direction and for a distance over
which they have control, and which result in a
temporary or permanent change of habitat.
(Williams, 1957)
Migration

3. Flight boundary layer
A layer of air at an altitude where wind speed remain
below the flight speed of insects
A. Migration within the boundary layer
Insects are capable of self direction
Insects engage in continuous wing flapping and
active forward motion
Eg: Butterflies, Dragonflies
(Srygley and Dudley, USA, 2008)

4. B. Migration above the boundary layer
Daytime migration
Smaller insects are carried upward beyond the limits of
their boundary layers by thermals rising from ground
Insect may not be in control of flight
Transported by wind
Eg: Aphids

5. Migration at night
No radiation thus no thermals
Insects depend on their own activity to carry them
upward.
Take off in large numbers soon after sunset
Eg. Grasshopper ( Aiolopus), locust (Schistocerca)

6. Control of migratory behaviour
 In Oncopeltus flight behaviour is stimulated by
intermediate level of JH
 JH increases more quickly in insects exposed to long day
lengths than short day.
 At low JH concentration flight behaviour increases
 At high JH concentration oogenesis occurs and flight
behavior come to end
(Rankin,2004)(Rankin, 1978)

8. The fall migration flyways of monarch butterflies in eastern
North America revealed by citizen scientists
From Canada and the United States to Mexico
(Elizabeth Howard & Andrew K. Davis, USA, 2008)

9.  In summer, found in Southern Canada and United
States
 Southward movement- Gulf of Mexico– July to
October (peak in September)
 On the way roosting in trees, clustering on cold
night and remaining until temperature rise above
13°C
 In warmer part- free flying and breeding occur
 But in colder (Florida and California)- roosting in
dense colonies in trees
 In Feb. and March – Temp. rises and return
movement to North

10. Distribution of Danaus plexippus in North America

11. The monarch, Danaus plexippus, a spectacular insect migrant.
Monarchs at their winter roost in central Mexico.
Roosts

12. Numbers of monarch roost observations from Journey
North Participants from 2005 to 2007, grouped by week

13. From India to Mozambique, the insect world’s
greatest migrant
 Dragonfly, Pantala flavescens
 Dragonfly moves Southwards by way of the Maldives every
year for breeding.
 Swarms starts with beginning of NEM in Maldives.
 The numbers peaked in November
and December.
 Dragonflies returned to India through
Maldives in the April due to SWM
(Charles Anderson, Britain, 1983)

15. Dragonfly migration from India to Africa
(Anderson,1983)

16. Locust
 Locusta migratoria - Europe, Africa, India, Pakistan,
Australia
 Schistocerca gregaria - Northern Africa and India
 Locustana paradalina and Nomadacris septemfasciata
- Southern Africa
 Patanga succineta - India , Sri lanka, Malaysia

17. Schistocerca gregaria
North central Africa to
Middle East, Arabia
and India
20 km2
swarm = 1billion locusts
30 million sq. km area in 64 countries
2,05,785 sq. km area in India

18.  The desert locust inhabit the dry areas of
Northern Africa.
 Downwind movement of swarm
 Spring breeding is synchronized with the
arrival of the cyclonic rains in Meditarrnean
area and local seasonal rains in Red Sea and
East African regions
 Summer breeding associated with rains at
the Inter-Tropical Convergence Zone
(ITCZ).
 Migration occur for breeding and food.

20. Types of swarm
Stratiform swarm : Flat
Flying within few meters of the ground level
Locusts are highly concentrated with densities 1-10/m3
Formed in absence of temperature gradient
Cool, overcast weather favours
Cumuliform swarm: Towering
Towering 1000m above the ground
Locusts are widely dispersed with densities 0.001-0.1/m3
Formed in presence of temperature gradient
Convective updrafts on hot afternoons promote

21. Years Loss in rupees
1926-31 10 crore
1940-46 2 crore
1949-55 2 crore
1959-62 50 lakh
1978 2 lakh
1993 7.18 lakh
Losses due to locusts in India
Dte. of plant protection, quarantine and storage, Faridabad

22. Migration of insects in
India

23. Phenology of Migration and Decline in Colony Numbers and
Crop Hosts of Giant Honeybee (Apis dorsata ) in Semiarid
Environment of Northwest India
 Migration of honeybee- survey at three year interval from
1984 to 2012.
 Presence of honeybee nests at main campus buildings and
trees.
 Immigration in postrainy season - October - Peak
flowering on Pigeonpea
 Foraging- Nov. - Dec. Toria
Dec. - Feb. Chickpea
Feb. - March Barseem
March- May Sunflower
Ram Chander Sihag, Hisar, 2014

24. Emigration - May to Mid July
“Why” emigration?
a) High temp. in summer (43-48°C)
b) Non availability of bee forage
Advantage of migration:
 Act as pollinator of more than 30 crop plants

25. Annual migratory and colony decline patterns

26. Bidirectional movement of butterflies at South
Eastern plains of India
 A ten meter wide imaginary strip for quantification of
butterfly at the way of swarm
 Number of butterflies passing through strip over a 15
minutes duration counted
 Migratory species: Catopsilia pyranthe
Catopsilia pomona
Papilio demoleus
(Ramesh et al., Kalpakkam, 2012)
Towards
North
Towards South

27. Bidirectional movement:
 Towards North
-during October due to NEM
-the swarm flew across the wind
Towards South
-during July due to SWM
-the swarm not only flew across the wind but
also flew against it.
-wind opposing movement reduce migration
(density) of butterflies.

29. “Why” migration?
 Avoidance of excessive rain due to NEM and
SWM
 To avoid competition at site of emergence
 To utilize availability of larval host plant
resources at destination site

30. Long distance migration of aphids and
other small insects in Northeast India
 Aerial netting at height of 150 m. during
November
 Yellow pan traps placed at ground level
 Movement of aphids from plains to hills in
spring on southwesterly winds
 From hills to plains in Autumn (Oct.-Nov.)
on northeasterly winds (Riley,1995)
Riley at el., UK, 1995

31. Flight paths for aphids migrating over aerial netting site at
Haringhata

32. Mean aerial densities( no. per 104
m3
) of aphids caught in
aerial net between 14 to 23 November 1992

33. Yellow pan trap catch

34. Losses due to aphids:
 Direct losses due to L.erysimi 20-50%
 Spreading viruses (chilli mosaic virus by Aphis
gossypii) and mycoplasma (sesame phyllody by
Orosius albicinctus )
“Why” migration?
 To avoid high temp. of plains
 To avoid winter temp. of upland area

35. Migration of butterfly in the reserve forest of
Nilgiri Biosphere Reserve
 Counts were made by surveyor for one minute at 20
minutes interval standing 5m away from path of butterfly
migration.
 The orientation of flight was from North-East to South-
West along banks of the river Karimpuzha
 Maximum density at 1200-1300 hr.
 Highest abundance during hottest period
(Mathew and Binoy, Kerala, 2002)

36. Periodicity of migrant butterfly
160

37. Species:
1) Appias albina darada
2) A. wardii
3) A. indra shiva
4) Cepora nadiana remba
5) Graphium sarpedon teredon
“Why” migration?
Depletion of host plant due to population outbreak
Availability of larval and adult food resources
(Drypetes and Polyalthia longifolia) at migratory
site

38. Remote sensing technology

39. Advantages of RADAR
 To detect insects simultaneously at a range of altitudes
that can reach more than 1 km AGL
 The large sampling volume
 Insects are unaffected by flying through the radar beam
 Gives information such as the size, shape, displacement
direction and body alignment of each insect target
 Continuous and autonomous monitoring of pest
migrations(Beerwinkle et al, 1995)
 Monitoring high-altitude insect migration
(Chapman et al., 2002)

40. Vertical Looking RADAR
The Rothamsted Radar Entomology Unit (RREU)
United Kingdom

41. Significance of migration
 Seasonal climate change makes habitat unsuitable
 In North temperate regions the winter is unfavourable
period, while in tropics dry season unfavourable for
insects
 Migration enables a species to face changes in the location
of its habitats
 Exchange of genetic pool takes place
 Increases the range of species

42. Conclusion
 Migration is of primary remarkable feature of insects to
overcome adverse climatic conditions
 Migration also occur due to unavailability of food
sources
 Migration is regulated by hormones
 Migratory patterns of insects helps us to know the weak
links in the life cycle and helps in control
 Detailed observations are required to clearly understand
the cause of migration in insects.

43. References
 Howard, E. and Davis, A. K. (2008). The fall migration flyways of
monarch butterflies in eastern North America revealed by citizen
scientists, J Insect Conserv. 147:170–174
 Riley, J.R., Reynolds, D.R., Mukhopadhyay, S., Ghosh, M.R. and
Sarkar, T.K. (1995). Long distance migration of aphids and other small
insects in northeast India. Eur.J. Entomol. 92:639-653
 Sihag, R.C. ( 2014). Phenology of Migration and Decline in Colony
Numbers and Crop Hosts of Giant Honeybee (Apis dorsata ) in
Semiarid Environment of Northwest India. Journal of Insects. 20:368-
377.
 Chapman, R.F. (1988). The insects: structure and function. Edward
Arnold (Publishers) Ltd, London.
 Johnson, C.G. (1969). Migration and dispersal of Insects by Flight.
Methuen and Co. Ltd, England.