122 



THE AGRICULTURAL NEWS. 



April 15. 1911. 



INSECT NOTES. 



PALM PESTS ATTACKING 

 SUGARCANE. 



THE PALM WEEVIL. In Circular No. 9 of the Depart- 

 ment of Agriculture, Trinidad, Dr. Lewis H. Gough gives an 

 account of the palm weevil, Rhyyichophorui pabimvum, attack- 

 ing sugar-cane in that island. 



From Dr. Gough s account it appears that the larva of 

 the palm weevil, which has long been known as the gru-gru 

 worm, has for many years been known to attack sugar-cane. 

 In 1828, the Rev. Lansdown Guilding recorded such an 

 attack for the first time; in 1847, Sir Robert Schomburgk 

 made a similar record in Barbado.s, and more recently this 

 insect has been reported as attacking sugar-cane in British 

 Guiana and Trinidad. 



The cut ends of cane plants seem to be chosen by the 

 adult female weevil for egg-laying, the rind of the cane 

 being apparently too hard to be penetrated by the ovipositor. 

 Older canes are probably attacked at some point where the 

 cane has been injured. 



The egg stage occupies only a .short time. Dr. Gough 

 states that he has observed eggs to hatch in less than forty- 

 eight hours. The larval period lasts about three months, 

 during which time the larva grows to a length of 2i to 

 3 inches. The cocoon is found in the ground, and is construct- 

 ed out of fibres of the cane. The pupal stage is stated to 

 last from two to four weeks. 



The remedies suggested for the control of the palm 

 weevil on sugar estates are (1) the cleaning up of all 

 pieces of cane at the places where the cane plant is chopped, 

 and at the loading places, and (2) the covering of the ends of 

 the cane plants in such a way that the weevil cannot deposit 

 eggs in them. In relation to the second remedy, a useful 

 substance for the purpose is mould or some compound which 

 would repel the insect. Flat planting of the canes would 

 accomplish the same object. The palm weevil does not seem 

 to be a serious pe.st of sugar-cane in Trinidad, although 

 it is widely distributed. 



c.\STNi.\ DAED.^Lus. Ctistnia daedaiiis is a large day- 

 flying moth, known as a pest of palms in South America 

 which has been reported to attack .sugar-cane in British 

 Guiana. 



A letter dated March IS, 1911, from Mr. J. Rodway, 

 Curator of the Museum, Georgetown, appeared in the 

 Dewerara Daily Chronicle, in which attention was called to 

 the fact that Castnia daedalus has, in one instance at least, 

 been known to attack sugar-cane: while the previously 

 recorded food plants of this insect are palms. 



The letter states that the adult is aliout twice the size of 

 Castnia liruf:, which has become such a pest of sugar-cane 

 in British (iuiana in recent years, and it suggests that effort 

 .should be made to prevent its becoming established as a pest 

 of canes. 



In the Ai/n'ciilfiirnl J\'ci'<s for January 22, 1910 (Vol. IX, 

 p. 2()), Castnia daedalus is mentioned as occurring in 

 Surinam as a pest of cocoa-nuts, and Castnia liens, the afore- 

 mentioned serious pest of sugar-cane in British Guiana, is 

 ■oted as attacking cocoa-nut and other palms in Trinidad. It 

 would appear that the transition from palms to .sugar-cane and 

 from sugar-cane to palms is not difficult for these in.sects. 



The nature of the attack on sugar-canes by Castnia 

 daedalus is not stated in Mr. Rodway's letter; but it 

 seems likely that the larva ' of this insect would occur as 



a borer, since that is the habit of the insects of the genus 

 Castnia. 



An interesting point in conne.vion with the occurrence 

 of species of Castnia as a pest is found in Sharpe's Insects, 

 Part 2 (see Cambridge Natural History, Vol. VI), where it 

 is stated: ' these insects are rare in collections; thej' do not 

 ever appear in numbers, and are generally very difficult to 

 capture' This volume appeared in 1899, a few years after 

 the occurrence of Castnia liens as a pest of sugar-cane, but 

 before this was known generally. 



THE CONTROL OF INSECT PESTS. 



The first of a series of addresses on economic entomo- 

 logy was given on March 2, 1911, at the Imperial College 

 of Science, by Mr, H. Maxwell-Lefroy, Entomologist to 

 the Government of India and sometmie Entomologist on 

 the Staff of this Department. According to an account of 

 the meeting contained in the West India Coviniittee Circular 

 for March 14, 1911, Lord Cromer, who acted as Chairman, 

 drew attention to the lack of men who had received field 

 training in the methods of combating insect pests. This 

 matter was continuallj' made evident to members of the 

 Entomological Research (committee, when applications were 

 received from various parts of the world for experienced 

 economic entomologists. Lord Cromer made reference to the 

 offer by Mr. Andrew Carnegie, to defray the expense for 

 three years, of sending three or four men selected by the 

 Committee to the LTnited States, for the purpose of observing 

 the methods that are employed in that country for dealing 

 with harmful insects. In the development of the plans pur- 

 suant to the scheme that it was intended to follow, experi- 

 ment stations would have to be established for the purpose 

 of giving experience to the workers employed in them, for 

 the demonstration of the practical value of economic entomol- 

 ogy, and lastly, for the provision of experts to be sent out to 

 the districts where they were required, so that they would be 

 able to make good use of their knowledge in the actual places 

 where the damage was being done. 



In his lecture, Mr. Maxwell-Lefroy drew attention to the 

 very great loss that was suffered in various countries, particu- 

 larly by agriculturists, through the harm done by insect 

 pests. Although the devising of means for combating such 

 pests was an inifjortant part of the work of the economic 

 entomologist, such work did not end here: it extended to the 

 mterests of industries where insects were kept for the pro- 

 vision of u.seful products, among these industries being silk 

 manufacture, bee-keeping and the lac industry. In relation 

 to these, much of the ert'ort of the future would have to be 

 directed toward devising improvements, as there was plenty 

 of scope for the employment of better methods of 

 production. 



The greatest amount of attention had, however, been 

 drawn to the work of the economic entomologist through the 

 recent discoveries of the [lart played by insects in the trans- 

 mission of disease. The lecturer pointed out the way in 

 which it was now fully recognized that the control of many 

 diseases, especially in the tropics, was itself a matter of the 

 control of the insects which had shown themselves capable of 

 carrying them. The subject was of the greatest importance, 

 for if the colonies were to be peopled by healthy races 

 capable of developing their immense resources, the first 

 consideration was to ensure the absence of disease as far as 

 possible, and therefore to conduct energetic campaigns against 

 all the lower forms of life that were proved to be capable of 

 carrying diseases. 



