116 (No. 88 ECONOMIC CONDITIONS which, when cut, is carried to a threshing floor in the fields and beaten out by women or trodden outby cattle, the stalks beingkept for fodder during the dry season .

On irrigated holdings the value of manure is not over looked. Primitive ploughs or harrows are in use in some districts. In spite of attempts on the part of the Government and private enterprise to introduce more up -to -date mechanical and labour-saving devices, little advance has been made in this direction . Pro bably in no country in the world is the cultivator more conservative and less willing to adopt modifications in his antiquated methods.

The native, however, thoroughly understands irriga tion , and has learnt by centuries of practice to be very exact in levelling operations, the making. of channels, and the training of water upon the irrigated patch .

Even here , however, he has much to learn as to the use of labour-saving devices ( see below , p . 117) .

The Locust Pest. - A serious difficulty with which the Sudan farmer has to contend is the annual appear ance of swarms of locusts , sweeping the country over which they pass bare of vegetation. It is the mature insect, in the flying stage, which does the greatest damage to crops, for at the larval or " hopper ” stage the locust prefers to feed on the leaves of bushes. When the bushes are entirely covered, however, the rest of the hoppers cluster round the dura stalks and do consider able damage. The horde of hoppers travels at regular times , usually from 7.30 a.m. to 10 a.m. and from 3.30 p.m. till sunset . The course of advance is always with the wind , and if the wind changes during the siesta period the march is resumed in a new direction.

This regularity of movement makes it easier to attack the pest in the hopper stage than later. The Govern ment has taken active measures to abate the nuisance, and the services of the officers of the Entomological Section of the Education Department at Khartum are always at the disposal of local authorities. As soon as the hatching of a swarm is reported, officials are sent to place food impregnated with poison across the path