260 



on the subject. Inspection of over one million coconut palms showed 

 1'07 per cent, so badly damaged by the beetles that death was inevi- 

 table. The percentage of infestation was found to be fairly constant 

 and the distribution general, neither altitude nor contiguity to the 

 sea making any appreciable difference. Small holdings, w^here cultiva- 

 tion is not carefully practised, were naturally in the worst condition 

 from beetle attack. 



Eggs of 0. rhinoceros are deposited for preference in dead coconut 

 logs and stumps, under bagasse heaps, in manure heaps and in old 

 rotten piles of coconut husks, where they hatch in 10 to 12 days. 

 The young grubs at once begin to feed and remain in the larval state 

 .from 130 to 155 days, moulting four times. The pupal stage lasts from 

 30 to 37 days, when the adults emerge and at once begin their depreda- 

 tions. Up to this point their function has been entirely that of a 

 scavenger. The beetles are very averse to light and hide in dark 

 crevices or in the earth in the daytime, coming out into the open at 

 night, when they are greatly attracted by light. Coconut is not the 

 only plant damaged, Corypha elata, Caryota wens (fish-tail palm), 

 Oreodoxa regia (West Indian royal palm), Elaeis guineensis (African 

 oil-nut palm) and probably Arenga saccharifera (sugar palm) being 

 attacked with equal avidity. The beetle, having reached a coconut 

 palm, invariably selects a point near the base of the petiole of the 

 central unexpanded leaves and works its w^ay into the interior. As 

 it works it feeds on the soft tissues by sucking their juices. As a 

 burrow is cleared out, large quantities of fine fibre are discharged, 

 which remain about the entrance and fall to the ground, indicating 

 the presence of the beetle. The burrow often reaches a depth of 

 about 12 inches. Coconut palms have only one central bud or gro^\^ng 

 point, and as this bud is in direct ahgnment with the beetle's tunnel it 

 frequently happens that it is cut into and so injured that the bud dies. 

 Prom the fact that the beetle requires only a few hours to enter and 

 perhaps fatally injure a palm tree, the total extent of its depredations 

 can be imagined. 



When coconut trees are severely injured by the beetles, it is advisable 

 to pull off all fruits and allow no flower-spikes to develop beyond the 

 falling of the staminate blooms. The pistillate blossoms that re- 

 semble small nuts and are unfertilised can then be readily seen and 

 removed. This will in many cases save the life of a tree that w^ould 

 otherwise succumb as a result of the added drain upon its vitality by 

 reason of its effort to produce fruit when all its strength was needed 

 to help its recovery from injury. It is probable that about 40 per 

 cent, of the trees that die as a result of beetle attacks might be saved 

 by this treatment. Beetles frequently pass from a wild plant to a 

 cultivated one, and in the absence of cultivated plants they can sustain 

 themselves on wild plants. In studying the life-history of this species 

 it becomes obvious that the favourable environment that allows it 

 to propagate and become such a pest is due almost entirely to the 

 activities of man. Lack of clean cultivation, leaving piles of husks 

 of cocoiiuts in the plantations or heaps of bagasse have frequently 

 been qui-^e clearly shown to be the direct cause of outbreaks of 

 0. rhinoceros. 



Natural checks of the beetle have very little influence. Eats eat 

 many of the grubs, domestic fowls and crows devour them when 



