43G 



can be prevented from becoming a grave menace to the banana 

 industry by careful cultivation. Under ordinary circumstances the 

 attack of the weevil is directed to the bulb of the plant, eggs being 

 laid on the surface of the bulb, below the ground-level,"j" the larvae 

 penetrating into the bulb, where the life-cycle is completed, the whole 

 cycle taking about a month. Observations and records all tend to 

 show that those parts of the bulb are attacked where the tissues from 

 some cause lack vitality. In every banana plant there is the old 

 bulb present, the fruiting bulb and the sucker, and in almost every 

 case of infestation the old bulbs, which are in a dying condition, are 

 attacked, while there is little tendency for the grubs to penetrate into 

 the more vigorous or actively growing bulb.* In badly infested 

 districts under examination, the bananas were found to be in a badly 

 neglected condition and infested with the fungus, Marasmius seniiustus ; 

 in these circumstances the weevil attacks are much deeper and more 

 extensive than in healthier districts, and even here the bulbs were 

 generally attacked at the base. It is suggested that experiments 

 should be made in a wee\al-infested area, small plots being planted 

 and thoroughly manured and cultivated against disease or injurious 

 influences other than the borer, when it is hoped that marked 

 resistance would be shown to weevil attack. Attention is drawn to the 

 fact that the alhed weevil, Metamasius {SjyJienophorus) sericeus, which is 

 found on bananas, was supposed to be a direct pest of sugar-cane, but 

 careful investigation showed that the insect only attacks unhealthy 

 and previously injured cane-tissue. In cases of deep-seated infestation 

 of the bulbs, which will generally be found accompanied by Marasmius 

 and imperfect cultural methods, it would be well to eradicate the 

 bananas, which could be done under the advice of agricultural 

 instructors. The destruction of the bulb-tissue would seem in that 

 case to be of primary importance ; this is probably best accomplished 

 by cutting down and slicing up the stems in the usual manner and 

 then digging up and slicing the bulbs, the slices being spread over the 

 ground and stirred at intervals to promote decay. Eggs will probably 

 be laid for preference on these slices, which must be cut the right 

 thickness so that they will have decayed before mature weevils can 

 develop in them. The insects might be attracted in such numbers 

 as to make hand-collection advantageous. Growers should be careful 

 to select only healthy planting material. The suggestion has been 

 made that immersing banana bulbs in water for about 36 hours will 

 kill all weevils present. If this simple remedy proves efficacious, 

 growers should adopt the larecauticn. More knowledge is required 

 concerning the natural enemies of the borer in Jamaica. The question 

 of introducing a Histerid beetle from Java as a control is also being 

 considered. Problems of dissemination of the pest and alternative 

 host-plants also need elucidating. The views expressed in this 

 memorandum are put forward tentatively and experimental evidence 

 is desired before they can be regarded as conclusive. 



t Other observers state that eggs are usually laid in the stem several 

 inches above the soil. — Ed. 



* In the Congo, where this weevil has recently appeared and has 

 destroyed considerable areas of bananas, M. Mayne found that it was the 

 young plants that were chiefly attacked [see this Eeview, Series A, v^ 

 p. 364].— Ed. 



