26G 



THE AGRICULTURAL NEWS. 



August 16, 1913. 



INSECT NOTES. 



SUGAR-CANE PESTS IN BRITISH GUIANA. 



A very interesting paper by .Mr. 11. ^V. J!, ^loore, has 

 recently been received, entitled, A General Report on Insect 

 Pests for the year 1912 — to Me.ssrs. Curtis, (Campbell it Co., 

 Sind Messrs. Booker Bros., McConnell it Co. 



The report deals almost entirely with the in.sect pests of 

 sugar-cane, and is based on investigation.^ carried out during 

 1912, on the estates of the firms to whom the paper is 

 addressed. The following abstract of the report is likely to 

 be of interest t« sugarcane planters throughout the West 

 Indies. 



The large moth borer (Castnui licus) wa.s present on 

 jnost if not all the estates, to a much less extent than in 

 1911, and its decrease constitutes one of the outstanding 

 features of the year under review. The number of moths 

 captured on sixteen estates was 296,214, and of caterpillars 

 *nd chrysalides 672,104: whilst on one plantation, where the 

 fecord was kept for moths, caterpillars and chrysalides 

 together, the number recorded was .50,5^3; the grand total 

 for the insect in the three stages on seventeen estates being 

 1,018,901, as against 2,384,430 for the preceding year 



The decrease in the numbers of this insect captured in 

 1912 is stated to be due in part to the extreme drought 

 ■which prevailed for nine months, and also to the direct result 

 of the excellent work of collecting in 1911, which greatly 

 reduced the numbers available for propagation. 



On one estate, nearly 200,000 caterpillars were taken 

 in the month of November 1911, whilst less than one third 

 of that number was captured on the same estate during the 

 ■whole of 1912. In certain fields, the proportion of infested 

 to non-infested stools in 1911 was as high as 1 in 4 or 5 

 as compared with 1 in 30 in 1912; nuany stools showed 

 the presence of two or more caterpillars per stool in 1911, 

 ■while in 1912 few such cases were observed. 



The collection of caterpillars and chrysalides from the 

 cane stools is considered the mo'st etticient direct method of 

 reducing the numbers of Cantni-i licus, and this aided by 

 the capture of the moths, by the erection in the fields of 

 bird-perches just after cropping, results in a great reduc- 

 tion in the numbers, if not in the practical extermination, of 

 this insect. 



COKCLUSIONS AS REGARD METHODS Oi' (;0NTROL. 



The conclusions arrived at in the report with regard to 

 the large moth borer are:^ — 



(1) Long continued drought affects the insect adversely. 



(2) The persistent and vigorous collecting of cater- 

 pillars and chrysalides in the stools of canes ie the most 

 effective method of fighting this pest. 



(3) The collection of the moths is a very useful 

 practice. 



(4) Birds may be encouraged by means of perches in 

 the cane fields, and these are useful aids in the control of 

 the large moth borer. 



(5) Continued warfare must be kept up against this pest 

 until it is reduced to very small numbers over a series of 

 ^ear.s. A decrease for one year should not be taken as a reason 

 for ceasing control operations. 



(6) Continueil efforts on one estate, or on a group of 

 estates may result in practically freeing them from Castnia 

 Jiriis, although in localities near by the pest may he abundant. 

 In such cases, however, the numbers can be kept down only 

 by persistent effort year after year. 



The small moth borer is stated to be the most impor- 

 tant pest of sugar caue in British Guiana, and to be more 

 abundant at present than it was, say, twenty-five years ago. 

 Under the common name of small moth borer are included 

 two species, Diatraei^ sacchanilis and D. canella. A list 

 of seventeen estates is given on which the practice of collect- 

 ing caterpillars and chrysalides by cutting out 'dead hearts' 

 has been carried out, the number recorded being 1-5,285,960 

 in 1912, as compared with 13.632, 65.J in 1911. 



It is advised that collecting should be commenced 

 at the earliest possible moment, in order to prevent, as far 

 as possible, the complete development of the larvae of the 

 first generation, thus largely eliminating the second and 

 third generations 



The above account will be continued in the next issue 

 of the AgrkiiUinal Xews. 



OAOAO THRIPS IN FLORIDA. 



The cacao thrips {Hdwthrips [Phj-sopus] nil, roc Indus), 

 which is well known as a pest in all the islands of the West 

 Indies where cacao is grown, has now made its appearance 

 in Florida, where it is assuming an important role on account 

 of its attacks on mango and avocado pear. In addition to 

 the West Indie.s and Florida, the red- banded thrips, as it is 

 called, is recorded from Ceylon, Uganda and Hawaii; it has 

 also been observed on plants from Mauritius in a greenhou.se 

 at Washington. 



An account of its occurrence in Florida, and a technical 

 description of the insect in its different stages of growth are 

 given by H. M. Russell, in Bulletin f>!>, Part .', of the Bureau 

 of Entotnologi/ United States Department of Agriculture. 



Reproduction is parthenogenetic during a portion of the 

 year, and bisexual at other times, the males being much less 

 numerous than the females. 



The use of black leaf tobacco extract and whale oil soap 

 is recommended for the control of the red-banded thrips, the 

 proportions being as follows: — 



Black leaf tobacco extract 1 gallon 



Whale oil .soap 1 fi). 



Water 50 gallons. 



The whale oil soap is first dissolved in a portion of the 

 water, the black leaf tobacco extract is then added, and the 

 solution diluted to make the full amount. This should be 

 applied as a fine spray at a good pressure, so as to coat 

 thoroughly both surfaces of the leaves and the pods. The 

 above mixture, used as a spray, has given good results in 

 Florida. 



Another formula that also has a satisfactory action is 

 the following: Take 1 part of the black leaf tobacco extract 

 containing 40 per cent, of nicotine solution to 1,500 to 2,000 

 parts of water, and add 1 lb. of whale oil soap to every 50 

 gallons of the mixture. This is sprayed on the trees in 

 a similar manner to that indicated above. 



At a meeting of the Board of Agriculture, Trinidad, the 

 subject of spraying cacao was discussed. The Ento- 

 mologist recommended spraying russet-coloured pods as 

 soon as they are observed, since this condition generally 

 indicates the occurrence of thrips. In connexion with the 

 cacao beetle pest, a spraying demonstration has been arranged 

 by means of which it is hoped that the interest of the plan- 

 ters may be fully aroused as to the practical value of the 

 operation. 



