299 



Plant Sanitation. 



in obtaining the necessary material. I have recently had occasion to recommend the 

 application of Paris Green on a somewhat extensive scale. It was important that 

 the treatment should have been carried out promptly. But, on enquiry in Colombo, 

 no sufficient supply of the material was procurable, and it was found necessary to 

 import the insecticide from Europe or India. The local firms assert that the 

 demand for such goods is too uncertain, and that it would not pay] them to stock 

 material that may be lying in their stores for indefinite periods. This being the case, 

 it will devolve upon the estate agencies to lay in their own supplies, and it is impor- 

 tant that this should be recognized. A delay of a few weeks may make all the 

 difference between success and failure in the treatment of a serious disease. 



" Case-worms " (often miscalled ' caddis-worms ' by planters) have been in 

 evidence during the past month. Specimens of Clania variegata, Psyche albipes, 

 Acanthopsyche subteralbata and hypoletica have all joined in the attack upon the 

 tea plant. On old tea, these caterpillars do not seriously affect the plant, but 

 when hosts of the young case-worms invade a clearing of young tea, the result 

 may be quite serious. They gnaw the bark of the young stems and branches and 

 cause an extensive dying back. In such cases an arsenical spray is clearly 

 indicated. A mixture of Paris Green with twelve times its bulk (by measure) of 

 lime should be applied as a spray, with water. 



Case-worms are the larvaj of various species of moths belonging to the family 

 Psychidai. The caterpillars construct cases, of very diversified forms (see Plate), 

 composed of pieces of leaves or twigs or fragments of bark fastened together with 

 tough silk. They carry this case about with them, exposing the head and front part 

 of the body only when feeding. In this case also they undergo the resting or 

 chrysalis stage. The male eventually emerges as an active moth, but the female 

 has no wings, limbs, or mouth parts, and remains inside the case and deposits her 

 eggs there. The males are usually very much scarcer than the females. I am just 

 now making a study of this interesting family, and shall be grateful for assistance in 

 the form of living specimens of case-worms from the different tea districts. The 

 term ' caddis- worm ' is wrongly applied to these insects. The true caddis is an aquatic 

 arva of a distinct order of insects. 



Experiments against " Shot-hole-Borer " on tea have been conducted with a 

 patent mixture sold under the trade name of " Smearoleum." It is still too early to 

 determine the effect upon the pest. But it is evident that the application of the 

 mixture would be far too costly for general use. It has to be applied with a brush, 

 and only a small number of trees can be treated by one cooly in the day. Moreover, 

 the oily coating has a distinct tendency to prevent the development of buds, new 

 shoots appearing only from areas that had not been covered with the mixture. 



A correspondent asks for suggestions for getting rid of "Red ants" 

 (CEcophylla smaragdina). He writes : " In one of my tea fields they are so bad that 

 I can hardly get the pluckers to work." MacDougall's solution will be found useful 

 in such cases. The nests should be broken open and the mixture (2 parts in 100 of 

 water) sprayed or syringed into them. It is even more effective if applied warm. 

 A second application may be necessary to finally rout the enemy. 



The black-headed Coconut caterpillar (Nephantis serinopa, Meyr) is again 

 giving trouble in the Batticaloa district. I am informed that the pest has 

 greatly increased within the last few years, and that, instead of being perio- 

 dic in its visitations, it now shows a tendency to become chronic. The pest 

 is at its height in March, which (in that locality) corresponds with the ter- 

 mination of the wet season. Removal of the infected fronds has been found 



