195 



Plant Sanitation. 



some eases— has resulted in the death of the tree. Any application that is of the 

 nature of an airtight coating must be injurious to such a plant as tea, in which the 

 bark is live right to the surface. Under the circumstances detailed above, I should 

 recommend the isolation of the estate— from its infected neighbours— by a thick 

 screen of ' Dadaps ' (Erythrina lithosperma) which are of rapid growth and do not 

 harbour shot-hole borer. If, from the commencement of the planting industry, 

 estates and individual fields had been separated from each other by effective 

 screens of jungle or introduced trees, we should have had little trouble in confining 

 and combating the pests which are now able to spread without let or hindrance. 

 It is to be hoped that rubber planters will take warning from the difficulties 

 experienced first with coffee and now on the large undivided areas of tea 

 plantations. 



Two species of 'Case-worms,' (Chalia doubledayi) and ( Acanthopsyche 

 hypoleuca) (see figs. 2 and 10 on plate facing p. 301 in the May number of this 

 journal) are reported to have caused serious injury to afield of tea in the Gampola 

 district. This same field was badly attacked last year also, and the trees so 

 weakened that they have never properly recovered after pruning. Such weakened 

 trees should be assisted with suitable manure. Paris Green would be the best 

 treatment for this pest ; but there are evident objections against the use of mineral 

 poisons upon tea that is in plucking. I have suggested that lime and sulphur 

 (dusted over the bushes) might act as a deterrent against the spread of the pest, 

 bxit this cannot be relied upon to kill the caterpillars upon bushes already attacked. 

 Collecting by hand, when the insects are in force, is almost useless. The newly- 

 hatched caterpillars are very minute and inconspicuous. They are carried from 

 field to field on the coolies' clothing. Case-worms have been unusually abundant ? 

 during the last two years, x^robably owing to the comparative failure of the 

 usual rains. 



Specimens of the Pyralid moth (Dichocrocis punctiferalis) have been bred 

 from caterpillars infesting the seed heads of the Indian millet (Sorghum vulgar e). 

 The caterpillars were feeding upon the ripe seed, amongst which they had spun 

 silken galleries. This species is the well-known 'pod-borer' of Cacao in Ceylon, 

 It has also been bred from the seed-heads of the Castor oil plant (Ricinus). 



I have received branches of the handsome flowei'ing tree (Amherstia) thickly 

 encrusted with a lac-insect (Tachardia albizziw). The pest may be kept in check 

 by the application of kerosene emulsion. 



A correspondent sends me specimens of a small ' Plea-beetle ' (Hypnophila 

 flavipennis), and reports that they are destroying Adiantum and other cultivated 

 ferns in a green-house. They will also attack Begonia plants. These beetles 

 acquire their popular name from their leaping powers, a habit which greatly 

 adds to the difficulty of capturing and destroying them. I have found the best 

 means of circumventing their activity to be to lift each pot gently and stand it 

 in a large tray or bath containing water with a film of kerosene. Then shake and 

 disturb the leaves of the plant, when the beetle will hop out and fall into the water. 

 This should be done day after day until all the beetles have been captured. The 

 larvae of the beetles are probably feeding upon the roots of the plants and will be 

 hatching out from time to time. But if this treatment is repeated whenever the 

 beetles appear, they will be unable to lay any eggs and the brood will be exter. 

 minated. Some weak Phenyle — or Jeye's Fluid — and water, poured on to the earth 

 round the roots will kill the larvae ; but this must be done carefully or the plant 

 will be injured. A more radical cure, if the building can be rendered practically 

 airtight, is to fumigate it with hydocyanic acid gas ; but this is a dangerous 

 operation and can be recommended only when expert supervis ion is available. 



