218 



THE AGrvlCULTURAL NEWS. 



July 



1904. 



INSECT NOTES. 



Grenada. 



The following is extracted from the report by 

 Mr. H. A. Ballou/B.Sc., on his recent visit to Gi'enada. 

 This extract deals with the thrips on cacao: — 



Tlirip.s of cacexo (Physojnis ruhrocinctus) has been 

 known in Grenada since 1898, when it attracted the attention 

 of the cacao planters, and specunens were sent to the British 

 Jluseuni for identification. Since that time, there have 

 been several outbreaks of this pest in Grenada and it has 

 also appeared in other islands. 



The following is a list of the i.ublished references to 

 'Thrips' on cacao in Grenada, most of which also contain 

 recommendations as to the treatment of the disea.se or the 

 use of spraying apparatus for applying insecticides : — 



(1) West Indian Bulletin, Vol. II, pp. 176, 181 & 288. 



(2) At/ririiltuvil A'ews, Vol. II, pp. 56, 66, 88, it 1.34; Vol. 

 Ill, p. 10. (.3) Grenada Official Gazette, 1898, pp. 121, 

 198 it 229; 1900, February 16; 1901, April 1.5. 



I visited Hope estate where the cacao was reported to be 

 badly attacked by thrips. I found that the latest serious at- 

 tack occuned in November and December 1903. In one iield 

 of about 2 acres the trees were entirely dead, and I was 

 informed that this was due to the attack of thrips. In other 

 fields many trees were dead and others had dead twigs and 

 branches on them, and no cause could be seen, but I was told 

 that they had been seriously attacked by thrips. Not many 

 thiips were to be seen in any field at the time of my visit, 

 but a few were i>resent in several different places, and trees 

 were plainly suffering from some cause which I could not 

 find, but I was a.ssured that they had been seriously attacked 

 by thrips during the last general outbreak. 



At the Botanic Gardens I saw thrips on the leaves and 

 pods of cacao, but not in sufficient numbers to do serious 

 damage. In driving from Sautuers to Hojie estate I saw 

 by tlfe roadsiile many fielils in which the trees showed the 

 leafless, apparently dead, twigs which are .said to be the 

 result of the thrips attack. 



Upon several estates spraying has been employed : rosin 

 wash, rosin com-pound, whale oil soap and kerosene emulsion 

 have all been tried, and fumigating has also been practised as 

 well. Fumigating is done by means of small bush fires on 

 which sulphur is sprinkled. The amount of sulphur used is 

 .some 5 or 6 It), per acre. It is impossible that this could 

 have any effect in killing thrips, and is probably merely time 

 and money wasted. Any sulphur fumes strong enough to 

 kill thrips in an orchard would pr(ilial)ly seriously injure the 

 leaves and would certainly render the atmosphere absolutely 

 unfit to breathe, so that the labourers would be unable to 

 remain in the vicinity of the fires. No experimental .siiraying 

 has been carried out, so that it is impossil:)le to say how 

 much good has been done by the use of any of the washes 

 tried. The spraying was done with different washes in 

 different places and no exact comparison can be made 

 between the different kinds of treatment. 



I am of oi)inion that the matter of first importance in 

 connexion with the control of this pest is careful experimen- 



tal work. An area of cacao should be chosen which could 

 be di\ided into a number of plots, all having the same 

 conditions of soil, drainage, exposure, etc. Each of these 

 plots should receive a particular and definite course of 

 treatment over a considerable period of time. This would 

 fnrni.sh more or less definite results and give an opportunity 

 ftir judging between the various materials used, and for 

 comparison of treated areas with neighbouring untreated 

 ones. The life-history of thrips should be carefully worked 

 out, and an investigation undertaken as to the food plants of 

 the species other than the cacao. I believe that experimen- 

 tal work of this kind is all that the Government can do in 

 the matter. Each estate owner ami proprietor will have to 

 make practical application of the knowledge furnished him. 



The Cotton Stainer. 



At this time of the year, when there is very little 

 cotton in the fields, cotton stainers may be seen in great f 

 numbers around the ginning factories, feeding ujion the ; 



cotton seed that has got scattered about the ground. In 

 St. Vincent and Antigua this has recently been specially 

 noticed. 



In St. "\'incent this circumstance has been turned to ,( 

 advantage. 'Where large numbers of cotton stainers have 

 collected on the waste cotton seed, they have been sprayed 

 with pure kerosene from a Knajwack sprayer. In this way 

 the number of cotton stainers may be greatly reduced in 

 any locality, and if each estate would make a practice of 

 scattering small amounts of seed near the estate buildings 

 and then spraying frequently, much would be accomplished. 

 Hot water is quite efficient for killing the cotton stainer, but 

 must be very near boiling when used, which is a serious 

 drawback to its use in many instances. On the other hand, 

 seed which has been treated with hot water will be no le.ss 

 attractive to the cotton stainer, while seed sprayed with oil 

 will not serve as a bait until the oil has all evaporated ; as 

 this takes some time, fresh seed will have to be put out, or 

 the insects in the neighbourhood will wander away and get 

 beyond the reach of future baits and sprayings. If this 

 l)ractice were general, it would probably gi\e much better 

 results than any field treatment, and the trouble and cost, 

 which would, after all, be very .slight, woidd be amply repaid. 

 It has been observed this year at several places in the 

 Windward Islands that the cotton stainers collect in large 

 numbers to feed on the seed of the Silk Cotton tree : when 

 they are so gathered together they may be similarly killed 

 liy means of kerosene or hot water. 



It is not definitely known how many different plants 

 the cotton stainers feed upon, but there are probably several. 

 In addition to the species and varieties of cotton and the 

 Silk Cotton, there are probably other plants closely related 

 to those on which the cotton stainers can live. 



The Chicken Hawk and Mole Crickets. 



According to Mr. Austin H. Clarke, the writer of the 

 notes on the r)irds of St. Vincent in the West Indian Bulletin 

 (Vol. V, no. 1), 'the common Chicken Hawk [a-oves, on 

 investigation, to be, perhaps, as much of a benefit to the 

 agriculturist as it is a pest to the poultry raiser, .since it 

 subsi.sts very largely on the mole cricket, sometimes as many 

 as twenty or more being dispose<l of at one meal. It appear.s,. 

 therefore, that if it be considered unwise to protect this bird, 

 at least no bounties or rewards should be offered to aid in its 

 destruction.' 



