334 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1944 
800,000 people died in the year 125 B. C. after a locust invasion. Great 
famines have been caused by locusts in India, China, and other coun- 
tries. As recently as 1930, losses of crops estimated at nearly 1,000,000 
pounds were caused by locusts in Morocco. In Nigeria, in the same 
year, 1,000 tons of grain had to be imported to prevent famine; in 
Tanganyika Territory 75 to 100 percent of native crops were destroyed 
in 1929, and in Kenya in the same year £200,000 had to be spent on 
relief from the famine caused by locusts and drought. 
These are impressive figures, but it may be argued that locust inva- 
sions occur only periodically, and that a distorted picture of their eco- 
nomic importance is obtained by considering exceptional cases. 
To assess the cost of locusts and grasshoppers to the world, the Anti- 
. Locust Research Centre attempted to collect statistical data for a 
10-year period, 1925-34, which covered both bad locust years and those 
free of them. Statistics of this kind were not easy to obtain, and only 
49 countries (out of 77 suffering from locusts) submitted them. Never- 
theless, the total was staggering, showing that crops to the value of 
£83,120,800 went to feed the locusts in 10 years. The losses would cer- 
tainly have been greater if no defensive measures had been taken, but 
the latter cost another 13 million pounds. On the basis of these figures, 
it was not an exaggeration to estimate the average cost of locusts and 
grasshoppers to the world at 15 million pounds per annum. To this 
must be added the enormous figure of unpaid labor which is used almost 
everywhere for large-scale defensive measures. The data on this point 
are very incomplete, but the number of man-days often runs into 
millions in one year and in one country. 
AGRICULTURAL PROGRESS AND LOCUSTS 
It has been argued that locusts and grasshoppers represent a danger 
only in backward countries, and that the advance of agriculture should 
inevitably lead to their disappearance as pests. A long interval during 
which the United States of America were almost free from grass- 
hoppers led some of the most eminent American entomologists to 
believe that agricultural progress had made a repetition of the grass- 
hopper plagues impossible. These hopes were rudely shattered in re- 
cent years, when grasshopper outbreaks recommenced on a truly Ameri- 
can scale. 
Moreover, there are definite cases on record where direct encourage- 
ment was given to locusts by otherwise excellent developments. The 
Danube delta, for example, had become unsuitable for locust breeding 
on a large scale toward the end of the last century, but recent regulation 
of the river channel resulted in the emergence of new areas of land 
which were quickly utilized by locusts, and an area which had not 
produced locust swarms for many years became again a source of 
