pkesiii)-:ntial address — section c. 39 



i 



However, most of the stories of eggs hatching after many years 

 have arisen from no better foundation than hoppers unexpectedly 

 appearing after the lapse of so many years since locusts were 

 last observed, and as I am now clear in my mind that locusts 

 may occur in considerable numbers unobserved, I discount these 

 stories heavily. Nevertheless I have records of eggs hatching 

 after the lapse of ten years that I do credit, and I think it not 

 at all uncommon for eggs to lie over one season. 



The Red Locust has not been suspected of having more 

 than one generation in tv/elve months, and there is no acceptable 

 evidence that its eggs retain their vitality into a second season, 

 nor that soaking rains are essential for their development. The 

 adult insects live through the winter, most of the time, it is 

 believed, in the shelter of forests or " bush," but occasionally 

 venturing abroad. In the spring they mate and move about 

 locally, or migrate in great swarms, evidently seeking feed- 

 ing grounds and favoural)le ])laces for eo;g deposition. Onlv 

 the few general migrations alluded to in a preceding paragraph 

 have been recorded, and it is really not known whether or not 

 the descendants of the invading locusts of 1895-1896 were ever 

 re-enforced by new invading swarms from a great distance. 

 Egg-laying has been observed in Natal in early October, but 

 early December is considered the normal time in that Province, 

 and hatching is expected about thirty days later. In the Cape 

 Province, egg-laying seems to average much later, and often to 

 be prolonged into February and March ; but hoppers in all 

 months from October to June have been reported along the 

 coast. Hatching in the abnormal months are. I think, owing 

 to belated and irregular development, there having been nothing 

 in the instances recorded to suggest a second generation. 



I have given this almost too extended outline of our two 

 locusts merely as a necessary preliminary to speculation on the 

 causes that underlie locust visitations in South Africa. Be it 

 understood that at irregular intervals, sometimes after no locusts 

 have been observed for over a decade, vast swarms sweep out 

 of the Kalarhari or down from uncertain regions in the north, 

 spread over a tremendous area that may extend to two-thirds 

 of the Union, do enormous damage to crops and to veld, and 

 that thereafter, for a series of a dozen or more years, extensive 

 areas are liable to be more or less devastated every season. In 

 general, the plague is at its worst two or three years after it 

 first manifests itself. 



One common feature that the locust problem in South 

 Africa has with the locust problem wherever else it occurs in the 

 the world, is obvious association with large tracts of naturally 

 arid country where the rainfall is both scanty and erratic. A 

 little reflection will, I think, satisfy you that a gregariously- 

 inclined migratory plant- feeding creature, be it springbuck or 

 locust, or anything else, has decided advantages for continued 

 existence in such a country over any similar creature that is 



