P8 



THE AORICULTURAL NEWS. 



FfiliKUAEV 15, 191S 



INSECT NOTES. 



REVIEW OF A REPORT ON INSECT 



PESTS IN BARBADOS. 



The Kejiort of ihe Local Department of Agriculture, 

 >!irbados, for the year ended March 31, 1912, has been 

 issiied as a Supplement to the OlVn-ial Gazette for Januarj- S-l, 

 101.'!. This report contains, among a large amount of other 

 inatltr, an account of work done during the year in connexion 

 with insect pests of plants, most of the information under 

 this head being found in that portion signed by Mr. W. 

 ZS'owell, Assistant Superintendent of ihe Local Department, 

 where it is arranged under appropriate headings. 



I'nder the headings Inspection of Imported Plants and 

 Seeds, and Fumigation of Cotton Seed, there will be found 

 brief records of the routine operations carried out in con- 

 ne.\ion with these lines of work. The only point of interest 

 -attaching to the paragraphs appearing under tliese heads is 

 that a scale insect new to the West Indies is reported to have 

 been discovered on cacao plants from St. Lucia. This inseit 

 i.~ I'seuilmniidia [AspidiotusJ frilolntiforiiii.<, Green, formerly 

 recorded fiom Brazil, in the Western hemisphere, and from 

 several Asiatic localities. 



That portion of the report included under the head 

 I'ungi Parasitic on Scale Insects, presents an interesting 

 account of the occurrence of the shield scale fungus {C'p/ial- 

 oyioriiiDi lecanii), the red-headed fungus (Sj-iliaerofiilht: 

 corcophila) and of two others which do not appear to have 

 been satisfactorily identified up to the time of writing the 

 report. The glassy star scale {Vinsonia stellifera) was 

 attacked by a fungus probably belonging to the genus 

 Aschcrsonia. 



(In connexion with this account of parasitic fungi and 

 scale insects it may be of interest to refer to the papers on 

 this subject presented at the eighth West Indian Agricultural 

 Conference held at Trinidad in January 1912 which appeared 

 in the Wei't Jndian JlullHin, Vol. XII, that by Mr J. It. 

 Bovcll, F.L.S., at p. 399, and that by Mr. F. W.South, B.A., 

 at p. 40;i.) 



The insect pests submitted to the Local Department with 

 the request for advice as to the control measures to be 

 employed have included scale insects on a variety of plants. 

 1'he use of scale-destroying fungi and sprays has been 

 recommended for the control of these. 



The cacao thrips (//e/iol/irip^^ [Physopus] ruh)-oriiictus^ 

 Giard.) is recorded as having been sent in on leaves of grape 

 vine, mango and rroton; Eutltrips insnlai-is, Franklin, was re- 

 ported on rose trees and bonavist; another species of Kuthrips 

 occurred on sweet potato, and lleliotlirips ltai'inor>-ltoidalis, 

 Bouche, on fiddlewood {Cit/"irix;/liiin i/}iadraniiulare). 



A mite which sometimes occurs in large numbers on the 

 young interuodes of sugar-cane while these are still enclosed in 

 the sheathing ieif base has been under observation during the 

 year under review. 'I'he attacks of the mite cause the surface 

 of the cane and the edges of the leaf sheath to become covered 

 with closely-set, minute blisters which are at first whitish, then 

 red and later reddish brown in colour. (A description with 

 figures of this mite has recently appeared in the JSn/lelin of 

 Ei'bji.ioloyii-al JitMurch for November 1912, where it is given 

 the name Tarsoi'i-mus spinipes, Hirst. In this connexion it 

 is stated that specimens of this mite were sent to England for 

 study by Mr. J. R. Hovell twenty two years ago. It is of 

 fairly common occurrence in several West Indian islands.) 

 ^[ention is made of the natural control of an attack of red 

 spider on sweet potatoes by the action of the larvae and 

 adults of a rove-beetle (Staphylinidae), as a result of which 



the red spider was reduced from a condition of extreme- 

 aliundance to one of comparative scarcity, within a week. 



An instance of complete natural control of the c mraoa 

 Aphis on melons by ladybirds and hymeiopterous parasites 

 is also recorded 



The discovery of the cotton leaf-blister mite in Barbados 

 in February 1912 is also noted. This pest, which had been 

 known for several years in other West Indian islands had not 

 previously leen found in Barbados. After the discovery was 

 reported by the Entomologist on the Start' of the Imperial. 

 Department of Agriculture, the oHicers of the Local Depart- 

 ment made a careful examination to determine the limits of the 

 infestation, which was found to occupy a large proportion of 

 the cotton growing area of the island, the south eastern district 

 being the only portion free from infestation. An area about 

 two miles wide and six miles long, lying along the coast to the- 

 north of Bridgetown, was distinguished as being much more 

 seriously infested than any other district. This is situated 

 some two miles or more from the point of its first discovery, 

 and it is stated that this section was probably fuUj' infested 

 in the season of 1910. This area probably includes the 

 original point of infestation. 



The method of the introduction is not known, but the 

 hypothesis is put forward that the leaf-blister mite may have 

 been brought to Barbados by birds. This is based oa 

 observation of the method of spread within the island, which 

 points to birds as the agents most likely to cause distributioa 

 within the limits of a cotton field and from one field to 

 another. 



The investigations recorded in connexion with the study 

 of the root borer of the sugar-cane (Diaprepes alihreviatus) 

 and the brown hardback i^Pkytalufi smithi) attacking sugar- 

 cane in a limited district in Barbados, are of considerable 

 interest. 



The root borer has been known as a pest for several jear.", 

 cliietly on one estate where the study recorded in the report 

 under review was carried out The chief points now presented 

 in addition to those previously known (see West Indian 

 Bull tin, Vol. IV, p. 37 and Agriviiltand Xeivs, Vol. X, p. 218) 

 have to do with the length of time that the grubs can live 

 without food, and with the discovery of the eggs in the field. 



It has been found that, when the larvae are deprived of 

 food by the digging of the cane stumps after the crop is reaped, 

 they penetrate deeper into the soil and there construct aa 

 earthen cell in which they lie dormant for some time While 

 the length of time which may be occupied in this manner has 

 not been determined, it has been found that after a period of 

 three months they are still alive and capable iif resuming 

 feeding as opportunity oflFers. 



The eggs have been found to be laid on the cane leaf 

 near the tip, where this has been split by the action of the 

 wind. The eggs are laid between two adjacent portions - 

 which are brought into contact and their surfaces securely 

 stuck together by an adhesive substance deposited by the 

 egg-laying female, the eggs being thus well protected. 



The collection of the beetles is mentioned as likely to • 

 prove the most efi'ectual means of reducing the numbers of 

 this pest, and it is recorded that during one week over 

 y,(iOO were captured on this one estate, from their hiding, 

 places at the bases of the leaves of sugarcane and corn and 

 among the leaves of pigeon pea and other convenient plants. 



The practice of early reaping of infected canes followed 

 immediately by the removal of the cane stools, and a rota- 

 tion of crops, are also recommended as control measures of 

 value. The following is quoted: It is only when the root 

 borer is present io some abundance that it can be regardeil as 

 a serious pest, and whore it does become abundant it can. 



