Economic impacts

The bands of wingless hoppers and adult locusts have insatiable appetites, consuming some 100 million tons of green vegetation in a single year.4

Following several years of successful locust breeding, the damage to agricultural production had become phenomenal.46 Late nineteenth-century European travelers reported that locust damage to crops and vegetation was responsible for causing famine.4. From the 1890s, reports of the pest devastations of food production meant that both the Germans and the British considered locust swarms to be a serious economic impediment to agricultural and rangeland development.46 From the frequencies of the outbreaks and sizes of the swarms, it was possible to use probabilities to estimate the potential damage to agricultural and rangelands.49 The damage to crops was expressed according to whether or not control of the swarms had been attempted, and whether or not it had been successful. The damage was expressed as a function of vegetation/crops consumed by individual locust swarms.50 Knowledge of the amount consumed was then used to estimate the extent of economic damage.’1

An average sized swarm covering a space of 182 square meters would consume green vegetation equivalent to a cow weighing 250 kg. A typical swarm covering 16 km2 and with a density of 30 locusts per nv, at a mean body weight of 1.7 g, would consume not less than 157 tons of green vegetation in a single day, while ten swarms covering 160 km2 would consume ten times as much of green food per day which is an equivalent of 150,000 mature cattle.52 The level of damage caused depends upon the development stage of the crops. For example, if maize is attacked and eaten when the seedlings are 7 to 14cm high, the loss of the crop would be total.’5 Locust invasion at the time of flowering of crops would result in major loss of the season’s crops, while infestations at the time of grain ripening would ruin the expected harvest. A locust attack at harvest time would result in the loss of a substantial proportion of the produce and if the problem was widespread, famine would be inescapable.’4 A 100 percent loss of crop production every ten years would be disastrous to local economies.” This situation was common before the colonial period.’6

The 1920s in East Africa coincided with periods of severe infestations by the desert and red locust. Losses to agricultural production in the three East African colonies attributable to locust swarms were estimated at 150,000 tons of grain in Kenya (worth £2 million) and in both Tanganyika and Uganda at 50,000 tons of grain (valued at about £700,000) annually.’' In Kenya alone, from 1928 to 1929, crop losses due to locusts amounted to £300,000 annually. The damage was equally severe in all the countries along the locust migration routes.’8 Between 1926 and 1931, the damage to crops in Africa was estimated at £7 million.’9 From 1928 to 1934, the estimated agricultural loss in Kenya was put at £800,000 and if control was lacking, the loss valued at £3 million would have occurred annually.60 Considering that agriculture was being promoted at the time, and the land under crop production was expanding, the costs could even have exceeded these estimates.61 The 1930s was a period of great destructions by desert locusts throughout East Africa. The swarms that arrived in 1930 wiped out 75 percent of the crops that had been ready to harvest. Mervyn Hill62 reported an event in January 1930 as follows:

In the afternoon, all may be well, the crops ripening to harvest and the cattle grazing contentedly. Then the sky darkens, as a vast swarm of locusts, miles across and miles deep, threatens from the horizon. At first it looks like a dirty smudge, like the drifting smoke of a forest fire or the gloomy murk of a sandstorm. Soon the locusts fill the air and man is virtually powerless to prevent their landfall if they so wish. If a large swarm settles for the night, there is little worth harvesting on the morrow and little for cattle to eat—they lay the earth bare to excessive erosion by wind and rain.

Like the case with agricultural lands, the damage done by locust invasions in grazing lands was enormous.6’ In the 1930s, the locust swarms consumed vegetation and wasted 9,600 km2 of rangelands in Lemek-Mara in Maasail- and. The combined effects of locusts and drought resulted in hunger that killed large cattle herds of the Maasai.64

The locust invasions accelerated during the period from 1931 to 1935. We have, however, better estimates of the damage for the later periods. Based on data from the Anti-locust Research Centre in Nairobi, Kenya, the desert locust swarms during 1942-1954 cost individual countries millions of British pounds.6’ In the Somaliland Protectorate in 1953, the cost of desert locust damage was estimated at £250,000, while in the following year (1954), the destruction cost £600,000. Over the same period, Morocco lost crop exports worth £4 million.66 In Ethiopia, damage to crops in 1958 was estimated at $4 million. In the northern and eastern regions of Ethiopia during the same period, locust infestation resulted in losses of several thousand tons of grain harvest, plunging the region into famine.6' On the Red Sea coast of Eritrea, F.T. Bullen68 reported the loss of 43,000 tons of grain in a single year—risking hunger for many people. In September 1958, swarms caused heavy damage to crops, with economic losses estimated at £600,000. Along the migratory routes from the outbreak areas (from the Middle East to East Africa) over 300 million people were adversely affected.69 The damage by locusts to crops and grazing lands required effective control methods.70

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