p. H. AwATi 271 



on different apple trees by Prof. Lefroy, who examined those trees 

 next day and found that no harm was done to them. It seems there- 

 fore that the creosote oil in the percentage used (-25 per cent.) is not all 

 harmful to the trees. 



{h) lis action. The action of this emulsion is two-fold and there- 

 fore very effective. As it is shown above, the soap solution by itself 

 kills 72 per cent, of the larvae. Its action is also explained. The soap 

 solution, by being mixed with the creosote oil, becomes a deadly poison. 

 The soap solution enters the tracheae and blocks the stigmata and thus 

 introduces the creosote poison into the body. It acts both internally 

 and externally, and thus it becomes very effective. There is no chance 

 of recovery for the larvae, as is the case with the soap solution. The 

 percentage of the creosote, however, seems to be fixed — "25 per cent, 

 being the optimum. Below and above it the results are not very 

 satisfactory. 



(c) Effects. They have been already dealt with. The death roll 

 by this emulsion is very great. 



XI. Enemies of the Apple Sucker. 



As far as I have observed there are no enemies. I have not been 

 able to see any parasite, internal or external, preying on it. The larvae 

 are healthy and normal, and I have not seen any malformation owing 

 to its being parasitised. So it is impossible to say whether there is any 

 parasite controlling the growth and spreading of this pest. 



Occasionally I have seen mites attacking the nymphs and adults. 

 The mites are red and large — like those which generally attack aphides 

 (aphis). Besides these mites I have not seen any enemy to the apple 

 sucker. 



XII. Immunity of the Apple Trees to the attack of the 

 Apple Sucker. 



There seems to be no reason why there should be immunity to the 

 attack. Immunity may be acquired or inherent. The apple suckers in 

 the adult stages do not make any damage, and therefore there is no 

 pathological response. The inherent immunity may be due to the 

 fact that the juices of certain apple trees may be distasteful to the 

 apple suckers, while those of the others are sought after with avidity. 

 It must be remembered that the real damage is done by the larvae 

 and not by the adults. The larvae suck the juices of the buds and 

 not the fruits. It seems from what I have observed that there is no 



