These examples suggest that reclamation of desert areas, which is most likely to 

 occur where the existing conditions already tend to create favourable locust habitats, 

 may not be an unmixed blessing, by making such habitats more permanent and provided 

 with a regular food supply for locusts. So far, this has happened only on a limited 

 scale, e.g. in Abyan and in Tokar, but if desert reclamation is to bring substantial 

 benefits, it has to extend to many more and to much wider areas, and the effects on 

 Desert Locust populations may well assume very serious proportions. Somewhat para- 

 llel cases are not unknown. The Rocky Mountain grasshopper (Melanoplus mexicanus 

 Sauss) can normally produce one annual generation in Arizona where it was not a seri- 

 ous pest until extensive irrigation and cultivation of alfalfa created a stable favour- 

 able habitat, making it possible for the grasshopper to produce several generations a 

 year; regular chemical control keeps the pest within limits, but at a considerable an- 

 nual cost (Uvarov, 1948). 



It should not be concluded, of course, that desert reclamation is undesirable be- 

 cause it may encourage the locust, but this danger must be borne in mind when desert 

 development schemes are considered. It should be possible to provide safeguards a- 

 gainst undesirable consequences of irrigation and cultivation, but the need for such 

 safeguards must be realised in time. 



The above considerations refer to reclamation of the desert itself, but the effects 

 of extension of cultivation in the marginal areas must also be mentioned with reference 

 to locust danger. At present, the possibility of keeping the Desert Locust under per- 

 manent control still remains theoretical, and extensive anti- locust campaigns are 

 necessary to prevent devastation of fertile regions by invading swarms. The strategy 

 of these campaigns aims at achieving maximum destruction of locusts at a season when 

 they are breeding in desert areas. To give a recent example, swarm breeding by the 

 Desert Locust in spring 1952 occurred over some 10,000 sq. miles of Arabian deserts; 

 large mechanised forces had to be used to control the infestation and some 9,000 hop- 

 per bands were exterminated. Swarms which would have arisen from these bands 

 would have spread over the fertile cresent of Middle East countries north of Arabia, 

 but not a single swarm was allowed to develop and crops were saved, although at the 

 cost of great efforts and very high expenditure. If crops were closer to the breeding 

 areas, it would have been extremely difficult to prevent their damage by hopper bands, 

 and the deeper cultivation penetrates in the desert, the greater are the chances of 

 serious losses during plague periods. Again, one should not argue against the exten- 

 sion of marginal agriculture, but it would be wise to realise the danger inevitably con- 

 nected with it. 



The main general conclusion which may be suggested by considering the Desert 

 Locust in relation to desert reclamation, is that while the latter is certainly able to 

 increase crop producing areas, it would also increase the risks of losing the crops, 

 unless repercussions of reclamation on certain members of desert fauna, such as the 

 Desert Locust, are realised clearly and before it is too late. 



The Desert Locust was taken in this paper mainly as a better known example of 

 desert fauna. There are many other members of that fauna which are also associated 

 with favourable ecological islands in the desert. An artificial increase of the number 



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