Plant Sunitivtion. 



During the latter half of May I made a tour through the coconut districts 

 of Batticaloa to study the pests of the Coconut palm. The following is a list, 

 iu the order of their importance, of the insect enemies observed during my visit: — 



Black-headed Caterpillar (Ncphantis serinopa, Meyer.) 

 Red Weevil (Rhynchophorus signaticollis, Chevr.) 

 Black Beetle (Oryctes rhinoceros, L.) 

 Scurfy Scale-bug {Aspidiotus destructor, Sign.) 

 White scale {Heniichionaxpis minor, Mask.) 



I have given the 'black-headed caterpillar' the first place, because, though 

 not so widely distributed as are the two species of beetle, the attack was very 

 acute at the time of my visit. On two adjoining estates— to the north of Batticaloa 

 town — every single coconut tree was more or less involved, and in the worst 

 parts the fronds were completely skeletonized (see Plate A.). On one of these estates 

 the moths were on the wing and were resting on the trees in thousands* They 

 seem to prefer the older drooping fronds. It was remarkable that no moths 

 could be found on the adjoining estate, though the caterpillar was present 

 there in full force. It is evident, from this, that the broods are not synchro- 

 nous, but appear irregularly. Lamp traps were being employed at night with 

 considerable success. Two kinds of lamps were in use : one — a powerful acetylene 

 burner projecting from the centre of a large tray containing water with a film 

 of kerosene, and others— small kerosene lamps supported on a brick in the middle 

 of a basin of kerosene and water. The more powerful light naturally attracted 

 the larger number of moths, but the smaller lamps could be distributed more 

 evenly through the fields, and the sum total of their catch was considerably 

 greater than that of the single acetylene lamp. The result of one night's work 

 was 169 moths in the tray of the acetylene lamp, and from 20 to 60 to each of 

 the smaller oil lamps. The size of the tray containing the water and kerosene 

 would seem to be a more important factor than the brightness of the lamp. 

 If of insufficient diameter many of the moths circling round the light escape 

 capture. For practical work a tray of not less than 30 inches diameter should 

 be employed. I am convinced that a large number of small kerosene lamps 

 distributed through the infested area will be more effective than a few more 

 powerful lights. 



A certain amount of discredit has been thrown upon the use of lamp 

 traps, it being stated that the resulting catch consists principally of spent mah s 

 and females that have already deposited their eggs. This is undoubtedly the cafe 

 with some insects ; but it varies with individual species. With regard to moths of 

 this coconut caterpillar, I was able to satisfy myself fully that fertile femalefl 

 were attracted and captured in large numbers. Disection of the captured females 

 showed the ovaries to be densely packed with eggs in different stages of develop- 

 ment. The result of such disection suggested that the eggs are not all laid 

 at one time, but in many small batches. Later experiments with living moths 

 proved that normal batches consisted of from 12 to 20 eggs. The eggs while 

 still in the body of the female are of a greenish tint ; but after deposition they 

 are pinkish It was only after a long search that the natural habitat of the 

 eggs was discovered. They are deposited amongst the frass and debris of 

 the larval galleries, and are more or less masked by a covering of down 

 from the body of the parent moth. The discovery of the position of the 

 eggs is of importance, as it shows that a removal of affected fronds or parts 

 of fronds— besides resulting in the destruction of the existing larvae and pupae- 

 will get rid of a very large number of eggs that would have given rise to the 

 succeeding generation. There must, however, be other localities for the 



