W. J. DowsoN 87 



unfolded leaf. The edge of the leaf is not eaten away but a cylindrical 

 hole is eaten out, the diameter of the beetle's body, from one side to the 

 innermost soft tissues, passing through each leaflet in turn. Consequently, 

 when the leaf unfolds a circular rent appears in each leaflet, the line of 

 holes being nearly straight. Very often the beetle manages to bore through 

 the midrib, in which case the end of the leaf falls over and rots away. The 

 pest can be so bad that nearly all the leaves present these lines of holes 

 with a number of the tips fallen over. Occasionally the beetle eats the hole 

 near enough to the growing point of the palm as to be the means of start- 

 ing a heart-rot which in its effects upon the palm is similar to the bud-rot. 

 Effective measures of controlling this pest were only devised after 

 the life-history of the beetle had been discovered. The female beetle lays 

 her eggs in old rotting stumps of the cocoanut palm or other trees in the 

 vicinity. Hence the idea arose of making beetle egg traps and, as the 

 results have shown, these have proved fairly successful if regularly 

 inspected. The traps are made by collecting all the old stumps and 

 decaying vegetation and packing them in pits in the neighbourhood of 

 the palms. The pits are roughly 2 feet deep and 10 feet across. It is 

 important to destroy all the rest of the rotting stumps and vegetation 

 not used in the construction of the traps, which would be used by the 

 beetles to lay their eggs. At regular intervals the traps are inspected, 

 and when found to contain a goodly number of larvae, a covering of sand 

 is placed over them and carbon bisulphide is injected into each, thus 

 killing the larvae. 



III. Sisal Hemp. 



Besides the cocoanut palm, sisal hemp, Agave rigida, var. sisalana, is 

 also grown in extensive plantations along the coastal belt. This plant 

 has borne in the past the reputation of being the only crop in East 

 Africa which possessed no enemies. Sisal was first introduced in 1895 

 in the form of bulbils from Yucatan by the Germans into German East 

 Africa (now Tanganyika Territory). 



In the extremely dry conditions of Yucatan the plant grows for 

 twenty or more years before producing its single inflorescence, after 

 which it dies down. Owing to this slow growth but few leaves are formed 

 each year, and hence only a few can be cut annually from each plant 

 for the decortication of the fibre. In Yucatan it is possible to make use 

 of the waste which is washed away by a stream of water and which 

 contains a considerable amount of sugar. The liquid is filtered and fer- 

 mented to produce a strong alcoholic drink. 



