BITING AND NOXIOUS INSECTS OTHER THAN MOSQUITOES 49 



furnish me with his views as to its probable utility in a very hot ami dry country like the 

 Sudan. His reply was distinctly iinfavourable to the fungus, and Mr. Theobald expressed 

 a similar view. Dr. Edington, however, suggested that it might be well, if locusts were found 

 dying in large numbers, to have their bodies sent to the laboratories where they could be 

 examined. In this way a fungus might, perhaps, be found suitable to our climatic conditions. 



Acting on this advice I informed the Civil Secretary, and notices were at once 

 distributed. Two interesting letters have, so far, been the result, one from the Governor 

 at Dueim, the other from Mr. Nevile, Manager of the Sudan Experimental Plantation 

 Syndicate at Zeidab in the Berber district. Major Butler wrote, " Some time ago a great 

 many locusts died at Shatt ; the people ate them and a great many of them were made ill." 

 An effort is being made in his district to obtain dead locusts for examination. Mr. Nevile, 

 writing November 6th, 1905, remarks, " I am glad to say that for the time being we are 

 practically free from these pests, though a little while ago we exterminated a considerable 

 swarm of small ones. During the last flight, however, we noticed a considerable number 

 of dead ones killed by the Tachina fly or the local representative of this insect, of which 

 I forward you a couple of samples bred from the maggots in the locusts." (These proved to 

 belong to the family Tachinidrp sp ?) " The latter were not dead when the maggots were 

 extracted. As, from what I read, this fly thrives in dry countries and is a considerable 

 help in reducing the number of locusts, it may be that in time it vnW wipe them out. 

 From what I hear there has not been a bad locust year since 1898 in this part of the 

 country, and this was the last of a cycle of three or four years. Again, I understand that 

 in tliis part of the country the duration of the present attack is quite unusual. In most 

 locust years heavy flights occur for a few days, usually in March, April and May, and then 

 disappear. TMs year they have remained from March to October practically continuously. 

 The worst locust years appear to coincide in some respects with the high Niles, e.g., the worst 

 attacks here have been in 1312,* i.e. (1894), 1316,* high Nile years (though there were none 

 in 1310*, 1314*), and therefore presumably rainy years. The fact that the locusts usually 

 appear here before the rainy season would tend to show that there was no connection between 

 the food supply in the immediate neighbourhood and their appearance. Possibly they have 

 had a rainy season in the Abyssinian highlands the year previously. Locust swarms here 

 always appear to come from the Kassala district and, according to local report, their visits 

 coincide with good rains there. Here locusts never appear in the winter which natives say 

 kills them off. On the Blue Nile, however, I think I have heard of vast swarms in 

 December, 1900. Any information you can give me on these points will be much appreciated 

 as they may have a direct bearing on the period for planting crops, and the frequency of their 

 visits is a matter of vital importance to capitalists flunking of investing in landed property 

 here." 



One was able to give Mr. Nevile some of the information he desired, at least, as regards causes of 

 the irregularity of locust visits. This is said to depend on three facts : — irregularity of 



. . . ... locust visits 



1. That the increase of locusts is kept in check by parasitic insects. 



2. That the eggs may remain (as already noted) more than one year in the ground and 

 yet hatch out when a favourable season occurs. 



3. That the migratory instinct is only effective when great numbers of superfluous 

 individuals are produced. 



* In the Mohammedan Calendar. 



