ijioi'oiri' OK rill'; kntoiiological section 131 



exce))t when in tlie adult sta-fic it ])asses the wliolo of its existence hidden within th(t stem 

 or the sheathing leaves of the )ilaiit it attacks. Some investigations liave been carried 

 out in Dongola Province witli a view to ascertaining whether it would not be possible, 

 in that region at any rate, for the farmers to lessen its numbers by concerted action. 



The seasons in Dongola Province are roughly as follows : — The main crop of the year is 

 tlie flood or demera. crop, sown at high Nile, and consists mainly of dura and maize. 

 It is harvested some four months later. The wheat crop is put in in December. The 

 winter or shitn-e and the summer or i-aifie crops are comparatively small and 

 miscellaneous but include a proportion of dura. 



When the demera crop is harvested, the second brood of borers is in the larval stage, The larvne 

 most of these larvte being within the stalks. A few, however, are in the roots. The stalks, ^,":^':", '" 



® ' ' ' dried t/unr 



which are known as (/ii.inaJi, and which constitute the staple diet of the farm live-stock stalks afiiT 

 throughout the greater part of the year, are removed from the cultivations and stacked, ^^'^'^^ 

 usually on the roofs of houses, but the stubble is left in the ground. The houses are 

 situated among the cultivations and the stock are fed close to the houses. Qiiagab is 

 not very palatable fodder and, consequently, stock prefer to eat only the tops and leaf, 

 and to reject the hard stems — those very parts, in fact, in which the caterpillars like 

 to take up their winter quarters. The i/iisaab from a demevd crop frequently lasts 

 until after the next demera crop has appeared above the ground. 



Occasionally, a strip of land is left with the stalks of the demera crop standing to 

 act as a wind-break to protect other crops. As many as seventy larvje, together with a few 

 pupae, have been taken within tlie short space of half an hour from a wind-break of 

 this kind. 



The dura stem-borer will sometimes attack wheat, and the larva? have also been found 

 wintering in d.n.kn stubble. 



A number of stalks containing larvae, from a demera crop was collected in Dongola 

 Province in February and placed in a breeding-cage in Khartoum. One moth emerged 

 in March, four in April, thirty-five in May and June, eleven early in July, and the last had 

 made its appearance by August 6, the total number of moths obtained from these 

 stalks being fifty-two. The natives assert that while the demera crop is always heavily 

 infested, there are comparatively few caterpillars to be found in the !<liifice and not 

 very many more in the ^aifie crops. Observations made in the field and on the times 

 at which the moths emerged in the breeding-cage confirm this statement. 



The obvious method of dealing with this pest is to collect and burn all the stalks and 

 stubble of the demera- crop while the borers are within — that is, inunediately after 

 the grain has been harvested. Unfortunately, however, this is not possible in Dongola 

 Province, for, it being an almost rainless region, there is little or no grazing for farm 

 live-stock, which are therefore dependent on this gussah for their existence. In districts 

 where grazing is obtainable, this could and should be done. I believe, however, that by the 

 careful and concerted action of the farmers in Dongola Province, the amount of damage 

 done by the borers could be lessened very considerably. The measures which should Measures for 

 be carried out to effect the control of the Ses-amia crefica are as follows : — ,,,p j,,,^^ 



(ii.) When any cereal crop is hai-vested, the stubble should be collected into heaps su-m-borer 

 and ijurnt. 



(//) In districts where the r/usnab is not needed for pi'oven<ler it should be collected 

 into heaps and burnt as soon as possible after the grain has been harvested. 



(c) When guniial) is fed to stock, the harder parts of the st(>nis are froquontly not 

 eaten — these should be collected every day and burnt. 



