156 15- P- UVAROV. 



of the Division of Entomology, Pretoria. Before proceeding to my own observations 

 on the morphology of the species, I will quote an extract from a letter from Mr. 

 Faure, dated 14th October 1920, which includes some very important and interesting 

 information on the question of the phases of L. pardalina. 



" My personal experience with the species began in the summer of 1914-15, 

 when scattered swarms began to appear shortly after the break-up of a prolonged 

 and very severe drought. Voetgangers {i.e., nymphs) of all stages and flyers occurred 

 together in loose swarms, and it was practically impossible to destroy them by the 

 usual method of poisoning. The swarms did not move in the usual compact forma- 

 tion, nor did they camp for the night in dense clusters. Many of the adults were 

 strikingly undersized, and a large percentage of both adults and voetgangers were 

 abnormally coloured. Only in swarms that approached the normal in density did 

 the typical orange and black colour of the voetgangers begin to show up. 



" Although I did not realize the fact at the time, I was witnessing the transition 

 from the grasshopper to the swarm phase. Towards the winter, that is in May and 

 June 1915, the flyers began to move about in fairly definite loose swarms, and they 

 laid their eggs in compact deposits, with the result that large swarms of typical 

 swarm voetgangers hatched the following spring. We received no reports that 

 winter of swarms of flyers coming into the Union from the Kalahari or anywhere else, 

 and the outbreak in the period September to December 1915 was very severe in 

 the area in which the scattered locusts had been observed the previous summer. 



" It was quite evident, therefore, that the invasion of September-December 1915 

 had arisen from locusts bred up within the borders of the Union. Formerly the 

 Kalahari Desert had been thought to be the chief source of our invasions of Locusta 

 pardalina. Now we are convinced that large outbreaks can and do arise within our 

 borders without the help of swarms coming in from the Kalahari. In the past, 

 huge swarms have undoubtedly come into the Union from the Kalahari, and no 

 doubt history may repeat itself in the future. But we no longer regard the Kalahari 

 as a sort of permanent breeding ground, and are now inclined to believe that it will 

 ordinarily only develop into a breeding ground if we allow swarms of flyers to escape 

 into it from the Union. 



"In 1917 I again saw scattered locusts from February to April, and another 

 severe outbreak of voetgangers occurred the following spring and summer. In a 

 general way it was a repetition of what had occurred in 1915, and realizing what was 

 going on, I was better able to make observations. 



" Locusta pardalina does not merely occur in scattered swarms and in compact 

 swarms — it also lives as a grasshopper, i.e., single specimens have often been collected 

 miles away from the nearest swarm and in seasons when no swarms have been known 

 to exist anywhere in the country. I have good reasons for believing that the species 

 is probably never entirely absent from certain parts of the Union. During the 

 past five years I have often searched for specimens during the intervals between the 

 occurrence of swarms, and in practically every case I have succeeded in capturing 

 two or three at least in say an hour's walk on the veld. Of course one should not 

 expect to find them late in the winter or during a bad drought. 



" The specimens captured singly almost always have the colours of the grass- 

 hopper phase, and they are as a rule'^a good deal smaller than swarm forms. Further, 

 I have frequently taken last-stage nymphs and newly-fledged adults living the life 

 of single grasshoppers. Although I have not been able to make a careful study 

 of the specific characters of these single living forms, I am quite satisfied in my own 

 mind that they are identical with the swarm forms. Again, these single forms may 

 occur in the district or on the farm on which swarms are present, and I have on 

 several occasions seen a few individuals with abnormal colours amongst a swarm 



