180 



The estate was divided into lightly, heavily and very heavily infested 

 areas, those along the border being kept separate. In those border areas 

 that were moderately attacked collection was only carried out for about 

 1| hours in the early morning and in the evening ; adults composed the 

 bulk of these catches. To check this work a gang of special collectors 

 went over the border areas once every 3 or 4 days. As regards other 

 parts of the estate, moderately infested gardens were visited once 

 daily and more heavily infested ones two or three times a day. 

 Collection was done on all possible occasions, by as many workers as 

 possible, and in nearly all weathers. European supervision was 

 constant. Pruning was done with the wund, as advised by Leefmans 

 [see this Review, Ser. A, v, p. 416]. 



A comparison between a portion of this estate and a similar portion 

 of a neighbouring one — where the campaign was not so intensive and 

 cost only three-fifths as much — shows that the value of the increased 

 yield was three times that of the extra cost, and furthermore that the 

 estate was rendered a more valuable property. 



Canter Visscher (W. A. E. A.). Het Uitzwavelen van zwaar aange- 

 taste Tuinen. [The Sulphur Fumigation of heavily attacked [Tea] 

 Gardens.] — Meded. Proefstation voor Thee, Buitenzorg, Ivi, 1917„ 

 pp. 16-20. 



On certain estates sulphur fumigation has proved very useful against 

 Helopeltis. Coolies placed in a circle around an infested plot were 

 provided with sticks to which sulphur cartridges were attached. A 

 cartridge could thus be held beneath each bush or twig. The men 

 gradually advanced towards the centre of the circle until the whole 

 plot had been fumigated. If the right time is chosen (about 6 p.m.) the 

 fumes will hang about the bushes for a considerable period. Each plot 

 was fumigated thrice on three consecutive afternoons using 11 

 cartridges an acre each afternoon. After a 5-day interval, during 

 ' which collection was effected daily, this triple fumigation w^as repeated 

 and again followed by collection for five- days. As a result the normal 

 collection of Helopeltis was soon found to require only 7 women for 

 4 acres owing to the limited number of insects present. In the event of 

 a windy afternoon fumigation may be carried out on the following 

 morning from 6 to 7 a.m., but is less satisfactory. On one estate this 

 operation was carried on for a period of six weeks on two occasions 

 only in 8 years, and the 700 acres concerned are still free from Helopeltis. 

 In another case six weeks a year was found necessary. The cost of the 

 sulphur cartridges was about 485. an acre for the six weeks, that of 

 wages being about lid. an acre for each day of fumigation. Collection 

 is a valuable measure during the East Monsoon [dry season] and even 

 if only a few specimens are captured then, the work is valuable, as 

 these are the brood-mothers giving rise to the individuals that occur 

 in the rainy season. The plants were also carefully manured so as to 

 promote vigorous growth. Prunings and other rubbish were burnt 

 without delay. 



As pointed out by Dr. Bernard in his preface to this and the preceding 

 paper, the success of this fumigation is evidently'dueto the circumstance 

 that the infested plots were of a size permitting them to be surrounded 

 by the operators. 



