A COMPARISON OF NATURAL CONTROL OF TOXOPTERA 
GRAMINUM IN SOUTH AFRICA AND THE 
UNITED STATES. 
By WiLt1aM Moore, 
Asst. Prof. of Entomology, University of Minnesota. 
During the past year, the author, while engaged as Lecturer 
in Entomology at the Potchefstroon School of Agriculture, 
spent considerable time in studying Toxoptera graminum in 
South Africa and its control there by natural enemies. As the 
results obtained have been somewhat different from those 
obtained in the United States, it is thought that a comparison 
of the conditions and the results would be of interest to Ento- 
mologists. 
Toxoptera graminum is found over certain large areas in 
South Africa but attracts the greatest amount of attention in 
the Orange Free State, Basutoland, and the western portion of 
the Transvaal. It seems to have been present, at least in the 
Free State, for many years, since the older farmers can remember 
the pest as long as they have been farming in the eastern portion 
of the Free State, known as the Conquered Territory. The 
earliest definite tecord was 1896, which year is distinctly remem- 
bered by a farmer who lost his entire wheat crop in that year. 
In the higher portions of South Africa, i. e., an elevation of more 
than 5000 feet, Toxoptera is either not present or is not present 
in numbers sufficient to attract the attention of the farmer. 
In the lower coastal regions, it also appears to be absent as, for 
example, along the coastal region of Natal. It is probable that 
the increased importance of Toxoptera during later years has 
been due to the destruction of the locusts which formerly 
swarmed over South Africa. There is little doubt but that the 
locusts destroying the grain and incidentally destroying Toxop- 
tera were responsible for the prevention of what might have 
been a serious attack during that year. Since the locusts have 
been destroyed, Toxoptera has had a better opportunity of 
showing the injury of which it is capable. 
In South Africa, there seem to be two forms of Toxoptera 
under normal conditions, namely, the winged migratory 
females and the apterous, viviparous females, the males and the 
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