THE DESERT LOCUST THREAT
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Document Number (FOIA) /ESDN (CREST):
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U
Document Page Count:
24
Document Creation Date:
November 16, 2016
Document Release Date:
February 4, 2000
Sequence Number:
1
Case Number:
Publication Date:
June 1, 1968
Content Type:
IM
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DIRECTORATE OF
INTELLIGENCE
Intelligence Memorandum
THE DESERT LOCUST THREAT
For Official Use Only
CIA/BGI GM 68-5
June 1968
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CENTRAL INTELLIGENCE AGENCY
Directorate of Intelligence
June 1968
INTELLIGENCE MEMORANDUM
The Desert Locust Threat
Summary
Africa and the Middle East are currently threatened
with an outbreak of locust plague. Concentrations of
swarming locusts have been reported in northeastern
Africa and the Arabian Peninsula, where spring rains
have been particularly favorable for breeding. The
critical period will occur from July through September.
By this time, spring swarms will have arrived in the
summer breeding grounds in large numbers.
The region has suffered four major locust plagues
in the last 60 years. Local rains and winds sustained
the most recent outbreak, which ended in 1962 after 12
years. Insecticides are used successfully to destroy
isolated swarms of locusts, but control techniques have
not been effective against full-scale pla=due conditions.
Note: This memorandum was produced by CIA. It was
prepared by the Office of Basic and Geographic Intel-
ligence.
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1. The Desert Locust Information Service in London has
warned that a maximum desert locust control effort will be
needed in Africa and the Middle East to prevent widespread
crop destruction in the summer and fall of 1968. For the
first time since 1961, the weather favors breeding on a
scale that threatens plague conditions. Swarming locusts
have been reported in central and western Saudi Arabia, in
the northern part of the Somali Republic and adjacent por-
tions of Ethiopia, and in the French Territory of Afars
the
and Issas. Scattered locusts have been reported along
southern coasts of Iran and Pakistan; along the Morocco-
Algeria border; in Yemen, Spanish Sahara, Mauritania, Mali,
Niger, and Chad; and on the Red Sea coastal plains of Ethi-
opia and Sudan (see Map 1). Although the locust is one of
the most intensively studied insects in the world, and
locust-control programs are effective for limited areas,
an incomplete understanding of plague dynamics coupled
with the vast area of incidence prevents effective control
of swarming locusts under plague conditions.
An Intensively Studied Insect
2. The scientific name for the desert locust, Schisto-
cerca gregaria, was first applied in 1793. Only since 1929,
however, have areawide data on desert locusts been recorded
systematically. Since then, reports of locusts Lfrom
rthe
field have been indexed and plotted on maps by Bureau
squares. The initial work was done by the of Entomology in London, now the Commonwealth Institute of
Entomology. In 1945 the Anti-Locust Research Centre of the
Institute was made an independent agency, and in 1958 the
Desert Locust Information. Service was formed within the
Centre with financial assistance from the Food and Agri-
culture Organization of the United Nations. In 1943 the
Centre began issuing monthly summaries of current infor-
mation and monthly desert locust forecasts.
3. Five regional organizations with 29 member nations
carry out control programs in Africa and the Middle East.
Only India and Pakistan belong to more than one regional
grouping. Cooperation in control exists among the coun-
tries within each organization, but there is no consistent
cooperation between organizations. Control programs and
reporting stop at borders, whereas locusts do not. The
regional locust-control commissions and their members are
listed below.
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Commission
Commission for Controlling
the Desert Locust in the
Eastern Region of the South-
west Asia Distribution Areas
Member Countries
Afghanistan, India, Iran,
and Pakistan
United Nations Food and
Agriculture Organization
Arabian Peninsular Desert
Locust Control Sub-Com-
mittee
Desert Locust Control Orga-
nization for Eastern Africa
India, Jordan, Kuwait, Pak-
istan, Saudi Arabia, Sudan,
United Arab Republic, and
Yemen
Ethiopia, French Territory
of Afars and Issas, Kenya,
Somali Republic, Tanzania,
and Uganda
United Nations Food and Algeria, Libya, Morocco,
Agriculture Organization and Tunisia
Northwest African Desert
Locust Research and Con-
trol Sub-Committee
Organization for Locust and Cameroon, Chad, Dahomey,
Bird Control Ivory Coast, Mali,
Mauritania, Niger,
Senegal, and Upper Volta
Scope of Problem
4, The desert locust has plagued Africa and the Middle
East since the beginning of recorded history. It presents
an unusual problem not only because it appears in great
numbers and has a voracious appetite, but also because it
can fly great distances within relatively short periods.
Although bands of hoppers may travel no more than several
hundred yards per day, swarms in the young adult stage may
travel 160 to more than 200 miles per day. Young adults
are capable of flying 10 to 12 miles per hour for periods
of 16 to 18 hours. In October 1945, swarms reaching Por-
tugal from southern Morocco on a strong southerly wind
flew continuously for 24 hours.
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5. Today some 60 countries are subject to invasion,
and in 30 countries the desert locust presents a serious
problem for agricultural development. Bands of young
hoppers and swarms of flying; adult locusts may cover
areas several hundred square yards or several hundred
square miles in extent. As a direct result of a locust
plague, 5 percent of the population of Algeria died of
starvation in 1866. A drastic situation of this nature
is not likely to develop today, but a plague would
severely strain the domestic food resources of an area
populated by more than 700 million people. In August
1957, an estimated 16 billion desert locusts invaded
Somaliland. Computed at one-third of a million locusts
per ton, and since locusts eat at least their own weight
in vegetation per day, these swarms destroyed 50,000
tons of vegetation each 24 hours. In 1958, swarms
invading Ethiopia ate enough grain to feed 1 million
people. In January 1964, swarms that covered some 500
square miles of Kenya contained up to 50 billion indi-
vidual insects (see Figures 1 through 3).
6. Natural vegetation is the major source of locust
food, since only 3 to 5 percent of the land area subject
to locust invasions is cultivated, but cultivated crops
may be totally destroyed by locust attack. Cultivated
plants that suffer particular damage under attack are
alfalfa, tobacco, sorghum, millet, beans, sugarcane,
cotton, citrus, and small grains. Man inadvertently
assists the locusts when he irrigates new land and pro-
duces green crops in areas subject to invasion. Such
is the case in southern Yemen, where irrigated fields
of cotton provide a convenient feeding area for swarms
of locusts moving northward from eastern Africa or south-
ward from Saudi Arabia.
Breeding Pattern
7. A major source of momentum for a plague of desert
locusts is the regional pattern of breeding and. movement.
At any given season of the year, new swarms are being
bred on local rains and carried on regional winds to new
breeding grounds somewhere in the locust realm (see Maps
2 through 4). Except as adverse natural conditions
occur, the cycle of breeding and movement is repeated
indefinitely.
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8... Rainfall and winds associated with the movement of
the Intertropical Convergence Zone (ITCZ) are key elements
in the breeding pattern of the desert locust, and variations
in the usual time and extent of movement of the ITCZ markedly
influence the upsurge and decline of the desert locust cycle.
In East Africa, winter breeding coincides with the short
rains that result from the southern movement of the ITCZ,
whereas spring breeding comes with the long rains, the north-
ern passage of the ITCZ, and the arrival of the southeast
monsoon. In northern and northwestern Africa, spring rains
are associated with westerly winds and cyclonic disturbances;
summer and autumn breeding in these areas coincide with the
ITCZ since it. lies near its northern limit, July through
September. The protracted monsoon rains of the Indian
subcontinent provide excellent breeding conditions for the
desert locust,,
Life Cycle
9, The life cycle of the desert locust is highly de-
pendent upon the coincidence of parent locusts with rainfall.
Moist sandy soil is required for laying and maturing the egg
and for producing green vegetation essential. for feeding the
young insect. The egg stage lasts 2 to 10 weeks, depending
on temperature. A newly laid egg contains less than half of
the water present when the hopper hatches. The young, wing-
less hopper is about half an inch long at birth and molts
five times before reaching the winged adult stage in 5 or 6
weeks At each molt, changes in form and color pattern
occur that can be easily identified. The mature adult is
a large insect; with body length of 2-1/2 to 3 inches, wing-
spread of 4 to 6 inches, and weight of 1 to 3 grams (see
Figures 4 through. 7),
10, One of the most unusual. characteristics of the
desert locust is that both hopper and winged adult may
appear in solitary and gregarious phases and may change
from one to the other. Individuals in the solitary phase
take on a uniform green coloration and adopt a routine of
night movement and day repose, As the name implies, they
generally move about singly or in pairs with little regard
for other locusts. When large groups of solitary locusts
are brought together because of wind conditions or hatch-
ing from closely spaced egg clusters, they may become
gregarious and take on a different appearance and pattern
of living. In the swarm the young adult is pink, and the
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mature adult .is yellow with a black pattern. Bands of
hoppers or swarms of adults move by day and settle at
night. Although swarms are produced from a collection
of solitary locusts, the number of such swarms is in-
significant when compared to the many that. result from
gregarious breeding,
11, New swarms of locusts usually form at the end of
the local rainy season or in the early stages of the dry
season? Young locusts leave the area of hatching soon
after reaching the winged stage and move on to the next
breeding ground in time to lay eggs at the time of the
local rain, Where the rainy season is long, as in
India and Pakistan, several generations may be produced
in one area in the same season,
Plague Cycles
12. There have been four major plagues of desert
locusts in this century (see graph, following page 8)0
The largest of these covered an area of 11?5 million
square miles that extends from Senegal to East Pakistan.
During the five major recessional intervals within the
same period, swarms were active in an area of only 6
million square miles (see Map 5).,
13, Plagues occur when rainfall and winds combine in
sequence to favor the breeding and movement, of locust
swarms, To prosper, a locust must find proper breeding
conditions, vegetation to eat, and moving air in which to
fly, Swarms are carried from one area to another with the
local rains. The locust population declines when the
highly variable rainfall arrives too early, too late, or
not at all, and when wands are out; of phase with breeding,
.Heavy infestation of individual countries may occur, however,
even when the total evidence of swarming is low. Swarming
in the recession area is a constant threat to cultivated
land and is a potential source of plague generation. The
recession area contains some of the driest and least, hos-
pitable landscapes in. the world, Not enough is known about
conditions in these vast, inaccessible areas to prevent
upsurges of swarming and outbreaks of plague.,
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Forecasting and Methods of Control
breeding area and
14. Desert locusts have no specific breeding over the
may swarm in any of the thousands of wadis sp. dcover th Bause 6 million square miles of the recession area
the 'migratory habits of the locust, a cooperativeteff rtnd
is essential to the success of reporting, orecang,
control programso Forecasts of locust activity made by
the head-
the Anti-Locust Research ~~~ateons aredbased on regional
quarters of regional orga ange
reconnaissance, analysis of plotted reports, a long-range ger-
weather-.f.orecasts, daily weather reporting,
Weather forecasting is
formances of locust. migio~u~~sacti Wevity, since the 'location
critical in predicting are as un-
predictable areas and the activity of swarms ar as-ica
predictable as desert ratbylthe ~k t.chybreport.ng net-
forecast:ng is handicapped
work in the largely uninhabited locust territory.
Coordinated air and ground reconnaissance on a
l'5 0 otential :for .achieving
.regional-scale offer the best p methodology. insights into locust ecology and control mroeethoidol p advcncet format on, butmuch
locustseoftenearre difficult to
advance e and fo to identify from the air and many of the
detect e
positive data must be gathered by ground teams moving out
AddiAdditional support
on leads radioed from searciicat;.onsto:f radar and remote
sensing are available as Radar tracking of Locust swarms
ing are perfected
was carried out by the British in the Persian Gulf in
1964., Attempts are being made to use information derived from weather satellites to identify breeding grounds and
to forecast locust-bearing
The Romans in North Africa attempted to control.
16
locust invasions by attacking them with branches and
were burned During
driving them into trenches where they
smoke and flamethrowers
swaTrmiBritish ng locuststroops The most effective programs
agaWorldinst War II
.
insecticides -- aldrin, dieldrin, and benzene
today apply
llexachlori.de -- with low:flying air cr aft, ,jeep-mounted
ra ers? ack turbine blower, hand
usters, d sap's broadcast
In addition, , b b p Because of the
by hand over known and suspeV~~abieeresult of locust;
dramatic nature and clearly
ro rams tend to spark the in-
ns of
terest .rsoo o:f f some lo omeulocal governments almost to the exclusion
wasteful insect pest infestations (see Fig 8
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17. The inadequacy of plague prevention and control
programs, however, is typified by the most recent
plague,
which persisted from 1950 through 1962 in spite of active
antilocust programs on a broad regional scale.
only after deviations from wind and rainfall ato nss t
s
blunted the thrust of the plague that isolated swarms
were effectively eliminated by insecticides a
the ground and from the air and by natural enemies on
as kites and storks. s such
18. Crop losses in reasonably restricted areas can
nonetheless be reduced by persistent control a
Programs must be pursued actively in recessionctivities.
well as when plagues threaten Unfortunatel years as
is no immediate threat some local 3'~ when there
give little support to control organizationts tend to
equipment maintenance, programs, and chemicalinvventories.
When plagues threaten, interest returns; but the fire-
brigade reaction is too late when an upsurge in swarming
is taking place on a large scale. The crisis is expected to be centered in northeasternAfricasduring
July, August, and September. The degree of success in
controlling locust invasion during this period will in-
dicate whether the desert locust cycle will remain in
recession or intensify into a plague,
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Figure 1. Hopper
s climbing field tent.
Hoppers cannot fly, but they scale any-
thing encountered.'
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Figure 2. Feeding adults weighing down a bush.
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Figure 3. Desert locusts swarming over airport
at Hargeisa, Somali Republic, on 3 August 1960.
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Figure 4. Length of a
desert locust egg pod
compared to length of
a regular cigarette.
Figure 5. Hopper at rest on head of
barley. In this stage, locusts are
most vulnerable to insecticides.
Figure 6. Adult desert locust, Schistocerca gregaria.
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Figure 7. Adult desert locust with wings extended.
The wingspread of a fully matured adult ranges from
4 to 6 inches.
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Figure 8. Locust control team
spreading poisoned bait in Iraq
desert.
Figure 9. Jeep with power duster
spraying eggfields in India.
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Figure 10. A Super Cub on a low-
level spray pass near Shiraz, Iran.
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DESERT LOCUST BREEDING REPORTED APRIL-MAY 1968
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DESERT LOCUST SPRING BREEDING AREAS AND MAJOR MOVEMENT, 1937-63
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DESERT LOCUST SUMMER BREEDING AREAS AND MAJOR MOVEMENT, 1937-63 Map 3
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DESERT LOCUST WINTER BREEDING AREAS AND MAJOR MOVEMENT, 1937-63 Map 4
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DESERT LOCUST INVASION AND RECESSION AREAS, 1920-64
Limit of swarming
in major recessions
Limit of invasion area
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a,.,_ n