340 | ANNUAL REPORT SMITHSONIAN INSTITUTION, 1944 
regarded as most inhospitable; establishing temporary field labora- 
tories; and gradually disentangling the many threads of the great 
problem. Nor was this extensive work uncoordinated, since practi- 
cally every year the experts and other representatives of the countries 
involved came together for a conference, to pool the results and to plan 
further campaigns. The accumulation of information on locusts at 
the International Centre, in the meantime, went on, with a steady im- 
provement in the unified reporting system, which by now covered the . 
entire continent of Africa and a substantial portion of Asia. All 
countries in that immense region submitted monthly reports on the 
locust situation. These reports were critically examined, summarized 
and mapped, so that all developments in the situation could be fol- 
lowed step by step. 
A feature of this international effort was its development without 
the signing of formal conventions and on a basis of direct collabora- 
tion between experts of many nations, with the ready support of their 
governments. 
The results of this teamwork, which is certainly unique in entomo- 
logical history, have justified the effort. At the outset of the investi- 
gations, practically nothing was known on the distribution of the 
different species of locusts in Africa, on their seasonal cycle and migra- 
tions, and particularly, on the origin and the course of their periodical 
outbreaks. After 8 years of intensive work, a clear picture of the 
whole problem became available, which has made it possible to formu- 
late an entirely new anti-locust policy, aiming at a radical solution 
of the locust problem. 
NEW ANTI-LOCUST POLICY 
The investigations just outlined have provided abundant evidence 
that the periodicity of locust outbreaks is closely connected with the 
periodical transformation of the harmless solitary phase into the 
dangerous gregarious one. Such a confirmation of a scientific theory 
may appear of no importance except to experts, but actually the theory 
has supplied the key to the whole problem. It was proved that the 
transformation into the gregarious phase can happen, in the case of 
each locust species, only in certain relatively restricted areas with 
peculiar natural conditions, and it is only in these outbreak areas 
that the first swarms can be formed. In the case of the African migra- 
tory locust it was shown that a few small swarms arising about 1928 
in a restricted area on the middle Niger in the French Sudan were 
the cause of an invasion which in 5 years swept over the greater part 
of the African continent (fig. 2). The outbreak areas of the red 
locust have been located in Tanganyika Territory and in Northern 
Rhodesia. With regard to the desert locust, it was found that its 
