138 



THE AGEICULTURAL NEWS. 



April 25, 1914. 



INSECT NOTES. 



ENTOMOLOGIST'S VISIT TO DEMERARA, 

 TRINIDAD AND BARBADOS. 



During February and March 1913, Mr. Geo. X. Wolcott, 

 Assistant Entomologist on the staff of the Porto Rico Board 

 of Agriculture, paid a visit to Demerara, Trinidad and 

 Barbados, for the purpose of observing the conditions of 

 sugarcane cultivation, the pests attacking the sugar-cane 

 plant, and to make observations on any natural enemies of 

 sugar-cane pests which might usefully be imported into 

 Porto Rico. Accounts of this visit have been published in 

 the Third Annual Report of the Sugar Producers' Association 

 of Porto Rico, issued as Bulletin No. -5, August 1913, and in 

 the Journal of Economic Entuniologif, for December 1913. 



Mr. Wolcott reported on the conditions under which 

 •cane is grown in the colonies visited, with reference to the 

 soil, climate and labour, and the bearing that these have on 

 general field practice and the abundance of insect pests. 



The report seems in the main to present a fairly accurate 

 account of the insect pests as these would be observed by 

 a visitor, but lack of familiarity with local conditions has led 

 to certain statements being made, bearing on subjects other 

 than entomological, which should receive some qualification; 

 as, for instance, the statement that the coral rock in Barbados 

 soaks up water from the sea and that this makes agriculture 

 possible in that island. 



In Demerara, the moth borer [including under this term 

 the ordinary form Diatraea saccharalis, and the related species 

 D. lineolata and B. canella\ is the most serious pest of 

 ■sugarcane. The importance of the injury caused by the 

 moth borer is recognized by planters, and energetic measures 

 are adopted for its control; and while this is not complete, 

 the loss from the pest's depredations is probably considerably 

 reduced. The measures adopted include (a) the cutting out 

 ■of dead-hearts, and (b) the collection of the caterpillars 

 and pupae, which are paid for at the rate of 6c. per 

 hundred, 700 being considered, by the boys who do the 

 -collecting, a day's work. The cutting out of dead-hearts 

 is continuous on account of the constant re-infestation caused 

 by the moths flying from the older ripening canes into the 

 £elds of young canes and depositing their eggs there. 



The moth borer is attacked by two species of egg 

 parasites (Trichogramma minutum [pretiosa], and Telenomus 

 sp ), and the boys who collect the caterpillars and pupae are 

 also paid for egg clusters which have not turned black, that is, 

 for those eggs which are not parasitized. There is also 

 a larger hymenopterous parasite, Iphiaulax sp , the adult of 

 ■which is conspicuous from its red, yellow and black colouring. 

 Its larvae are found attacking above 1 per cent, of the 

 caterpillars of the moth borer that are collected. Tachinid 

 flies have also been bred from moth borer pupae. 



Mr. Wolcott emphasizes the fact that the moth borer is 

 not controlled by its natural enemies and the artificial control 

 measures combined, the insect being, in .spite of these, the most 

 serious pest which the Demerara sugar planters have to 

 contend with. 



The only other serious pest of canes observed in Demerara 

 was the giant moth borer, Castnia licus. This insect is much 



less abundant and injurious than it was a few years ago. The 

 capture of the adult moths by gang.s of boys armed with nets; 

 the collection of grubs and pupae from the stalks and from 

 the stumps when the canes are cut; and the flooding of the fields 

 for .several days in case of very severe infestation, are practical 

 control measures that give good results. The control thus 

 obtained can only be maintained by persistent efforts along 

 these lines. 



The weevil borer [Metaniasius hemipterus), termites, and 

 the sugar-cane mealy-bug {Pseudocuccus calceohiriae), were all 

 observed but were not considered serious pests, especially when 

 compared with the destructive moth borer. 



In Trinidad, the froghopper (Tomaspis varia) was the 

 most important pest observed. Mr. Wolcott found it not at 

 all surprising that the froghopper should be abundant in 

 Trinidad, in view of the common agricultural practice of 

 allowing grass and weeds to grow in abundance in the fields 

 and traces, and of abandoning diseased and infested fields 

 allowing them to remain as breeding places for this and other 

 insects. The following paragraph is quoted: — 



' The whole environment is ideal and could not be better 

 for tlie propagation of large numbers of froghoppers and other 

 pests of cane. When the managers of the estates come to 

 realize the importance of cleaning up the grass and weeds in 

 the cane fields, there will be a most noticeable reduction in 

 the injury to cane by insects and more particularly in 

 the injury caused by the froghopper. Because of the lack 

 of sanitation in the fields the froghopper is a difticult pest to 

 control and is rendered all the more diflicult because of 

 the lack of vulnerable places in its life-history.' 



The young froghoppers live on the roots of cane, grasses 

 and other plants, beyond the reach of insecticides. The 

 eggs are laid on the ground in the lower layers of trash 

 where many would escape if the trash were burned. The 

 adults are stated to be too small and active to be captured 

 by collecting with the net. The work with the green 

 Muscardine fungu.s {Mdan-hiuHm anisopliae) was observed 

 and the methods of producing the spores in culture cabinets 

 and applying them in the field are described. 



On several estates, culture cabinets are in operation, in 

 which the fungus is grown in trays containing layers of 

 cooked rice. The application of spores in a tield on a larce 

 scale is made from blowers mounted on a railroad flat car. 

 On one estate over 500 acres have been dusted with spores 

 of the fungus. The results of these large scale applications 

 have not been reported upon, but in examinations already 

 made as to the effect of the fungus on the froghoppers very 

 high percentages killed have been found, and in one instance 

 at least 95 per cent, of the nymphs (larvae) in the stool of 

 cane were found dead and covered with the characteristic 

 green spore masses of Metarrhizium. 



The predaceous bug (Castolus plagiaticollis) from Mexico 

 and the two native egg parasites are mentioned as being 

 more or less efficient as natural enemies. 



The giant moth borer (Castnia licus) was observed 

 and considered to be next in importance to the froghopper 

 of all the pests of sugar-cane in Trinidad, and as being 

 probably more abundant than in Demerara. The only 

 control measure practised was the collection of the adults by 

 means of nets. 'It is impracticable to flood the fields from 

 which cane has recently been cut, no attempt is made to 

 collect the full-grown larvae and pupae from the stools of 

 cane, and the young larvae are not cut out of young cane,' 



