266 



THE AGRICULTURAL NEWS. 



Ai.asT 15, Idli. 



INSECT NOTES. 



SUG-AR-CANE PESTS OP THE LEEWARD 

 ISLANDS. 



During the early part of last year there appeared a series 

 of articles in the Aijvicultwal Neirs (see \o\. XII, pages 

 106, 122, 138, 154, 170 and 186) entitled 'Root Borers and 

 Other Grubs in West Indian Soils', and the information there 

 presented was afterwards brought together and issued as 

 Pamphlet Xo. 73, with a considerable nvmiber of illustrations 

 added. 



Under the heading which appears above, information in 

 regard to certain of these pests and other sugar-cane insects 

 has been issiied as Pamphlet No. 75. This pamphlet fur- 

 nishes an example of the manner in which information with 

 regard to a certain subject may lie accumulated over a long 

 period of time: at first new facts appeared slowly and later 

 with greatly increasing frequency. 



The body of the jjamjihlet is divided into two parts, the 

 first which is intrf)ductory and historical, consists of a brief 

 statement of the pests of sugar-cane which were known to 

 occur in the Leeward Islands previous to and for a short 

 time after the establishment of the Imperial Department of 

 Agriculture. The remainder of the pamphlet, which com- 

 prises the larger part of it, deals with insects which have 

 recently come to be, known as pests of sugar-cane in those 

 Lslands. 



The pests which are dealt with in the first part of the 

 pamphlet are the moth borer, the shot borer, the weevil borer 

 the cane fly and the mealy l)ugs. Those which are dealt with 

 as more recent pests of sugar-cane are the following; — the 

 Antigua lirown hardback, the St. Kitts brown hardback, the 

 Leeward Islands root borer and termites, ilention is made 

 of the Barbados brown hardljack, the Barbados root borer, 

 the ordinary black hardliack and certain parasitic wasps 

 because of the bearing Avhich a knowledge of their life history 

 and habits would have in the consideration of the Leeward 

 Islands pests. 



The Antigua brown hardback (Lachnosterna sp.) has 

 been known in Antigua for .several years, principally liy the 

 injury caused by its grubs to certain crops, and from the 

 occurrence in the soil of fields in which the growing plants 

 were sickly in appearance. This has resulted in the opinion 

 being formed that this insect is connected with the unfav- 

 ourable conditions observed. 



The Antigua brown liardback is a Ijcetle of the ordinary 

 hardback type, light Ijrown in colour, about i-inch in length 

 and about ;^-inch in width; the legs are moderately long and 

 slender, the eyes are large and black, the. hind end of the 

 body has the appearance of having been cut off square acro.ss. 

 The larva of this beetle is a white grub of the ordinary type; 

 ■when full grown it attains a length of about an inch. The 

 head is brown: there are three pairs of .slender legs; the body 

 is widest just behind the head, somewhat narrower a little 

 behind that, while the end of the abdomen is large and 

 swollen. This insect is known to occur only in Antigua at 

 present. 



It is in the larval or grub stage tliat this in.sect causes 

 the greatest amount of damage, feeding upon the small roots 

 of sugar-cane and Indian corn, and attacking onions and 

 potatoes. It is as a pest of Indian corn that this species 

 of Laclinosterna causes the most injury, although it is 

 a cane pest of some importance. It is suggested that 

 Indian corn may be used as a means of reducing the numbers 



of this pest in agricultural lands, especially where it is pro- 

 po.sed to grow sugar-cane and other crops known to be attacked 

 by it. 



It has been found that when Indian corn is planted at 

 such a time that the crop reaches maturity during December 

 or .January, consifl^rable numljers of the Lachnosterna grubs 

 are congregated about the roots of the plants. These can 

 easily he collected by pulling the plants and searching the 

 soil among the roots and in the near vicinity. Trials of this 

 method which have been made in Antigua have shown that, 

 in cases of moderately severe infestation, an average of five 

 or six grubs per plant has lieen found, and these have been 

 collected at the rate of about 1,000 per acre, and at a cost 

 of \d. per hundred, or lOtf. per acre. 



The applicatinn'of such a method of control as this is 

 exceedingly simple. It is nece.s,sary to remember that the 

 grubs of this insect, so far as known at pi'esent, all come 

 to maturity about ihe same time, which is at the beginning 

 of the year. Fields which are known or suspected to be 

 infested may l>e planted with Indian corn at such a tinie 

 that it will ripen at the time when the gruljs are nearly full 

 grown. The corn should then be pulled and careful search 

 made for the grubs which .should be collected and destroyed 

 when found. It should be borne in mind, however, that this 

 niethijd of control is of value only when care is exercised to 

 destroy the grubs at the proper time. 



The St. Kitts brown hardback (Lac/oiosteina patrueih) 

 is, in general, similar to the Antigua form, but is much smaller. 

 This insect has been known in St. Kitts only since 1912, when 

 it was discovered in considerable numbers in the soil of can(! 

 fields in that island. It is not known how much injury it 

 causes and it is to be regarded perhaps more as a potential 

 pest than one whose capabilities for harm have been definitely 

 proved. Laclinosterna palruelis is known to occur in 

 Haiti, San Domingo, St. Kitts and Dominica. 



A similar insect which occurs in Barbados is very 

 efficiently held in check in that island by a small parasitic 

 wasp. This is the Barbados bro«ni hardback {fhy talus 

 smifhi) the parasite being Tiplda parallela. This same 

 beetle has been introduced into Mauritius where without the 

 controlling influence of the parasite, it has developed into 

 one of the most serious of sugar-cane pests. The same 

 parasite occurs in St. Kitts where it is lielieved t(5 attack 

 Lachnosterna patruelis and it is proljably clue to the effect 

 of this parasite that the St. Kitts brown hardljack is mjt 

 more generally known as a sugar-cane jjest. In Antigua, no 

 parasite is known to attack the lirown hardback and careful 

 search in the vicinity of infested fields has failed to reveal 

 the presence of the parasitic in.sect wliii-h is common in 

 Barbados and St. Kitts. 



The Leeward Islands root borer (Exopt/taimiis esuriens) 

 is an insect which has been generally kiKn\ii throughout the 

 Leeward Islands for many years; liut it is only within the 

 last two or three years that it has been known to lie a pest 

 of sugar-cane and other crops. In fact it is only during the 

 the present year, 191-t, that the relation.ship between certaiii 

 grubs attacking the underground portions of cane stools and 

 this dark grey weevil has been definitely estal:>lishe<l. 

 Mr. F. Pi. Shepherd; Agricultural Superintendent, St. Kitts, 

 has reared the adult form f)f the insects from grubs in the 

 cane stools. .\s already stated, Exophthahmis esuriens has 

 been for a long time a well known insect in the Leeward 

 Islands. Although it is a weevil, that is to say an insect 

 in which the licad is prolonged into a snout or beak, this 

 insect is often called a hardliack, a term ^\hich leads to 

 a good deal of confusion in those islands. 



