The diseases and pests of the rubber tree . with a pair of long,thick, clubbed hairs, stand-ing out from the body andprojecting downwards, sothat when at rest it hadthe appearance of a smallcentipede. It was not,however, sufficientlynumerous to warrant anymethod of treatment otherthan hand picking. In Sumatra it is re-corded that caterpillarsbelonging to the groupusually known as Bagworms, or Case worms,have attacked renewing^ *? bark about a month old, two and a half to three centimetres above the tapping cut,and have caused holes resembling neglected tapping particular species con
The diseases and pests of the rubber tree . with a pair of long,thick, clubbed hairs, stand-ing out from the body andprojecting downwards, sothat when at rest it hadthe appearance of a smallcentipede. It was not,however, sufficientlynumerous to warrant anymethod of treatment otherthan hand picking. In Sumatra it is re-corded that caterpillarsbelonging to the groupusually known as Bagworms, or Case worms,have attacked renewing^ *? bark about a month old, two and a half to three centimetres above the tapping cut,and have caused holes resembling neglected tapping particular species concerned in this case was Psych&{Acanthopsyche) sneUeni. It builds a conical house, aboutfifteen inilUmetres high, covered with minute fragments ofbark (Plate VI., Fig. 3). As a rule this species feeds on thedead bark and lichens, but in the case recorded some of thecaterpillars had extended their operations to living female insect does not leave its house, and the eggsare laid within the conical case. Consequently collection. Fig. 37.—Tubes of a bark-eating caterpillar. PESTS 237 and destruction of the cases destroys all the females andeggs. Mites The occurrence of mites on nursery plants of Hevea wasfirst recorded by Arden in the Federated Malay States. Someyears later it was again noted by Ridley and Derry inSingapore. The leaves of the seedlings became irregularlytwisted and distorted, one side of the leaflet often beingshorter than the other, and the leaflet curved to one examining the under side of the leaf the tissue betweenthe veins was seen to be swollen, the veins appearing green ona grejdsh background. The mites occurred on the under sideof the leaf, but were not abundant. They were white, semi-transparent, with three brownish marks on the back. The damage was confined to seedlings, especially thosewhich for any reason were weak. Overcrowding in thenursery was said to be, in great part, a condition under whichinjury occurred. Frequently the lowest th
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