58 



I'll! AGRICULTURAL NEWS. 



February 13, 1915. 



INSECT NOTES. 



PESTS OF CACAO. 



The Following is a summ i oJ thi nott on insect pests 



-of cocao ni Hall's l referred to in 



insect notes in the last issue e Agricultural Neivf. 



The West Indian Mole criel - as tiidacfylus,) 



which is known in British and Dutch Guiana, and in the 

 Antilles, is at times a serious pestof young cacao plants in 

 the nursery and field. The mole cricket feeds underground 

 on roots. The young and adult forms tunnel through the 

 soil, ranging in depth from just beneath the surface to a loot 

 or more. Tin sorts, ven those that 



epted as f 1 are often nibbled enough to be 



injured. Cacao si d just at the point of 



juncture of the stem and root. In this way it happens that 

 many plants are killed bj a few mole crickets in one night. 



Sinn ly the young cacao plants are attacked by the mole 



cricket, the remedy for plants in the field is simple. 



young plants may be raised in pots in the nursery, 

 being carefully protected from this insect until they are of 

 sufficient size and strength to escape injury. They are then 

 planted in the field. 



The nurseries may be kept comparativelj free from 

 mole crickets by frequent turning up of the soil, and the 

 destruction of the inserts, in which the common fowl is 

 very useful. Poison maybe applied also as a poison bait, 



which is made by mixing 3 IK of arsenic with 100 ft), of 

 horse-dung, and distributing this in the soil. This amount 



is recommended for 1 acre. 



The cacao tree is subject to attacks by borers in most 

 countries where this crop is grown. 'The life history of 

 these different enemies varies in detail, but in many respects 

 their mode of life is the same, and accordingly, the light 

 against the various borers proceeds everywhere along the same 



general line. 



•The beetl ' moth lays itaeggs against the stem, or 



,,,. I,, often ina little hole made for the purpose in 

 the bark. The larva or worm lives for some time in the bark 

 or in the wood, and damages the tree to a greatei or smaller 

 extent. Often the presence of one borer may cause the 

 death of a whole branch, which then looks as if it had been 



killed by lire, as all the brown and dry leaves it-main hanging 

 on tiie twigs. Whole trees, e-pecia'U young ones, may 

 be killed in this way when the borer lives in the stem. 

 At present the general waj of fighting the borers is to remove 



the "worms" <•! larvae, cutting awaj the Lark by means of a 

 knife until the worm is exposed. On many plantations 

 , gang of trained worm pickers is kept for this purpose. 



[f possible, these men also collect the perfect insects whether 

 beetle or moth hut generally the number of captured 

 perfi t insects i- -mall in nson with the number of 



■captured worms.' 



The l.oring insects which attack cacao in different 



countries are described as follows: — 



The Wot Indian cacao borer (Strirastoma depreuum) 



is one of the worst pests of cacao in sot f the Antilles, and 



m various countries in South America. The Glenea borer 

 (Glenea novtmtjuttiatn) is the mosl common and most 

 destructive kind of cacao borer in .lava. The Pelargoderus 



,., i, , /■. largndi rut bipum tatut), and the Monohammus I tie 



(Monohnmiifut fislulator) rat k m \t to the Glenea as serious 

 borers of cacao. In Ka in allied Monohammus borer 



(ifonohammus rm 4 recorded as a pest of this crop. 



The large Catoxantha beetle (Catoxantha bicolor) has also 

 been a borer pest in lava, and it is known to occur in British 

 India. Shot borers of the genus Xyleborus are recorded as 

 doing damage to cacao at times in certain countries, 

 Trinidad an d .1 iva. The larva ol a Bombycid moth, 



[/.,„ era i f} u i. which is fairly common in -lava, is at till 



a serious borer in cacao 



i i| the insects which atta md fruits.the 



Helopeltis is the worst ,in Ueylon, and only second in impor 



e in Java. There are two speices l/elopeltis thi ivor.i, and 

 //. antonii, the former of which is prevalent in very hot 

 climates while the latter in the more common species In the 

 cooler regions. 



The eggs of these insects are laid in the young fruits, 



and at times in the lender twigs. 



Thelarvaeand adult- feed upon fruits, twigs, and leaf 

 stalks of the cacao, but not on the leaf Mad.'. The mouth 

 parts are of the suck iug kind, fitted for piercing plant tissue 

 and sucking "U> the juices. 



During the drj season the numbers of Helopeltis 

 small, but in the rainy month- they increase to enormous 

 numbers and cause ^reat damage. 



The fighl against these insects is rendered more diffi 

 because they live on many different plant-. 



The methods of control consist in collecting and burning. 

 The collecting is done by means of a stick of bamboo with 

 a ring "i bamboo or a kind of fork at the end. The ring has 

 a diameter of aboul •'! inches. This is passed through 

 a cobweb until it i- more or less covered with web, and 

 it is then used by the labourers to catch the adult II lopeltis. 

 The viscous juice of the .lack tree is sometimes used in place of 

 cobwebs. Burning is accomplished bj means of a bamboostick 

 filled with kerosene, and fitted with a cotton wick. With 

 thi- as a torch, the fruit are lightly scorched over, and many 

 Helopeltis are killed, hut neither this nor the catching 

 method is very satisfactory. Helopeltis seem to have very 

 lew natural enemies, and no diseast - are known which exercise 

 any control over them. 



It is stated that an ant, Dolichoderui bituberculatus, 

 Mays, has been introduced into cacao fields with marked 

 success in reducing the numbers of Helopeltis, although the 

 am does not attack the Helopeltis. The author does not 

 say, however, why or how the introduction of large numbers 



of the ant accomplishes the result. 



The Kind bug (SMberyella singularu) is stated to be 

 the worst insect pest of cacao in Kameruu. This is also 

 a -inking insect, which puncture- tin- hark or rind of young 

 twigs and inflicts serious injury. Good results in controlling 

 this insect have been obtained from spraying with a mixture of 

 Paris green ( 10 grams), kerosene <■> litres), soap 1 1 kilogram), 



lime (j or 2 kilogram-), and water ( Kill litres). A 1 per cent. 

 decoction of tobacco has also been used with success, and 



1. inning, as iii thecase.of Helopeltis, is likewise effective. 



The Mbqguilla is the worst pest of cacao in Ecuador. 

 This is an unidentified, hemipterous insect, which in both 



larval and adult stages I I on the .level, .ping pod. 



Every puncture made by the mouth parts of these 

 insects results iii a discoloured spot, and when these 



spots are numerous! as thej often are, the whole pod 

 turns black and does not develop properly, The pest has 

 been known in I'.. na.loi- for the past twenty-five years, and 



at present occur- throughout the entire coast region. In 

 some -easoiis it i- . jeilOUS that practically no sound .-., 

 IS secured. Very little is known al.oiit the life history of 



this insect, and no effective methods of control seem to be 

 known. 



Leaf eating caterpillars are not serious pests of cacao. 



