42 



THE AGRICULTURAL NEWS. 



January :?0, 1915. 



INSECT NOTES. 



INSECT PESTS OF COCO-NUTS. 



In the firsl number oi the present volun E the 



Agricultural News, two I ks have been reviewed which 



deal with important crops of tropica] countries. One of 

 these, Coco-nuts, by Copeland, was reviewed at page •>; 

 the other, Cacao, by van Ball, at page 20. Each of 



these 1 k> i tains a summarized account of the diseases 



and pests of these crops, respectively. The accounts of the 

 fungoid diseases were reviewed briefly in the last issue of 

 this journal (see page 30). The present issue contains a sum 

 mary of the account of the insect pests of coco-nuts; that 

 referring to those ol cacao will appear in the next number of 

 tlu- Agricultural News. 



i 0( ii \ ITS. 



The principal pests of coco-nuts are the black or rhino- 

 ceros beetle {Qryctes rhinoceros), and the red beetle, or Asiatic 

 palm weevil ( Rhynch< phorus Ji > rugineus). 



On/ctes rhinoceros is a shiny, dark-brown or practically 

 folack beetle, ranging in length from •'«> to 60 nun., with the 

 usual size between 10 and 50 mm. The male is the larger, 

 and is also distinguished bj the prominent horn on the 

 dorsal surface of the head, which in this sex is sometimes as 

 much as one centimetre (J-inch) in length, while in the 

 female it is smaller, often inconspicuous. The life-cycle 

 probably varies in length, certain writers on the subject 

 (Copeland amongst these) believing that in some cases it may 

 not occupy more than seven months, while others hold the 



■ opinion that the larval life al y may extend over "a period of 



two years. 



The eggs are not described The larvae reach a length of 

 1 decimetre (about 1 inches) when they enjoy particularly 

 favourable conditions. The larvae live in decaying vegetable 

 matter of all kinds, and the cocoons are formed in the same 

 situations. 



The injury to coco-nut trees is caused by the adidt 

 beetles, which eat their way into the bud, starting at the 

 •bases of the leaves. 



The means of controlling this insect ate the destruction 



•of the beetles in the tree or their removal by the use of 



.a wire probe: the destruction of their breeding places 



l>y the removal of all accumulations of rubbish; and 



by means of traps, which consist of holes tilled with 



specially prepared vegetabli refuse and mould, which furnish 

 satisfactory luce ding places, these being regularly examined, 



and the hectics, cocoons, larvae, and eggs collected and 



deal royed. 



This last method i- believed to he the most effective 

 means of controlling the black beetle References to this 

 beetle have been made in tie- Agricultural Ntws, Vol. XI, 



pp. 2 IS and .'ITS, and Vol. Mil, 'p. HI. The last of these 

 gives an account of the successful Use of a parasitic fungus iii 



i In- beetle traps, which Kills many of the larvae. 



The red beetle, or Asiatic palm weevil (Rhynchophonu 

 Jerrugineus) is related to the West Indian palm weevil 

 ^R. palmnrum), ami attacks cooo-nul trees in the same way. 



The red beetle is said to he the most deadly insect pest of 

 coconuts in the Philippines, but since it cannot attack sound 



trie-, it i- not the hardest to combat. 



It- length ranges from about '■'< to more than 5 



centi in- (I! to j inches). Its colour varies from reddish 



to almost black. I attacks the coco-nut ami other palms, 



hut is not known to infest plant- of other group-. 



The length of the life-cycle i- various!} estimated to 



cover a period of from ten week- to about one year. 



The red hectic i- not able to penetrate into the tissues 

 of a healthy coco-nut tree, hut take- advantage "I injuries of 

 all sorts, which result from any breaking of the surface. The 

 holes of the rhinoceros hectic, wounds resulting from 

 hurricanes, tire-, careless or unnecessary pruning, all offer 

 means of access to the egg-laying female. 



it has been found that the removal of old leaves, and the 

 firing of the tops in an attempt to check other insects or 

 disease, result in attack by this pest. 



The methods ol i bating this insect include, (1) all 



precautions against injuring the coco-nut tree, in which, ol 

 course, the control oi the rhinoceros beetle plays an important 

 part: (2) th<- removal and destruction of all infested coconut 

 or other palm tree- (."i extracting the beetles ami larvae 

 from their burrows and places of concealment in the tree; 



(1) the use of hait and traps, which consists in the felling 



and leaving exposed on the ground, under suitable conditions, 



of any dead coco nut or other palm known to he attractive to 

 the insect, until eggs have been laid in them and the larvae 

 have hatched, when the trap material is destroyed, preferably 

 by tire. Mangoes crushed in coco nut milk and water, and 

 exposed in shallow dishes are also said to have been recom- 

 mended as a trap. The use of poisons, such as carl 



bisulphide, cyanide of potassium, and hydrocyanic acid has 

 been tried for the control of this insect, hut without practical 

 results. 



A number of other beetles, including some weevils, are 

 also mentioned as being pests in the East, and reference is 

 made to those which occur in the American tropics. 



The most serious leaf-eating hectics mentioned are small 

 beetles of the family Sispidae, which both as larvae and 

 adults feed upon the leaves, and are the cause ol serious injury 

 to the trees. 



One of these, Bronthitpa froggatti, is stated to he con- 

 sidered by I'Yoggatt as certainly the worst pest the planters 

 in the Solomon Islands have to fight in their young coco-nut 

 plantations. The result of the attack is that the leaves are 

 reduced to skeleton- connected bj .lead membranes before 

 they are well unfolded. In Eastern Java the same, or a nearly 

 related -pedes, attacks the coco nut leaves in a similar way. 

 In the Solomon Islands gangs of boy- are kept at work 

 shaking soap and keuosene wa-h into the -till folded leaves. 



In tin- related genus, Promocotheca, three species are 

 known as coconut pests: P. cumingii in the Philippines, 

 P. an'iqua in New Guinea, and P. opicicollis in the New 

 Hebrides. 



The Philippine species is a -mall beetle fr To to 10 mm. 



in length. It is sluggish in habit, and does not fly readily 



on being disturbed. 



Tie adult beetles crawl between the f olded-up leaflets 

 of the young leaf, and eat -mall spots between the veins ol 



the leaf. 



The damage done by the larva is greatei than that done 

 by the adult. The eggs are inserted bj the adult female just 

 beneath the epidermis of the leaf. The larvae, on hatching, 



deiietrate into (he tissue where t hey feed, and pupate late, 



Tile -pot. eaten In | he beet les. and those eXeaVatcil b)'t)),; 



