SOME INSECT PESTS IN THE WEST INDIES. 



63 



trees m the cacao plantation it was subsequently found that the great 

 boles of the Immortelle trees {Erytlirina umhrosa), whose glorious 

 flowers formed a beautiful feature in the landscape at the time of my 

 visit, were badly infested with the same kind of scale as that which 

 wae attacking the Castilloa. The inference to be drawn from this 

 was, therefore, that the insect in question had migrated from the Im- 

 mortelle to the Castilloa, though it is important to note that the trees 

 in question were generally growing very widely apart, and it is difEcult 

 to explain how the young lice (larvae) of this Ooccid could have travelled 

 so far and have sought out pi'actically every rubber tree in the planta- 

 tion. Some of the young scale may have been wind-borne, and others 

 may have been carried by other agencies, such as birds, insects, or 

 even man ; but it is impossible that the infestation could have become 

 so general by such foreign agencies as I have indicated. 



The owner had already taken practical measures to check the spread 

 of this pest. All the infested trees on his estate had been treated with 

 a coating of lime and salt in the following proportions : — 



Air-slaked lime ... ... Two parts 



Salt ... ... ... One part 



with water added to make it into the consistency of cream. This 

 mixture was applied to the tree trunks so as to completely cover them. 

 The result proved highly satisfactory. An examination of the scale 

 which remained upon the trees showed that a very large percentage of 

 the insects had been killed. It was only in those places where the 

 lime had peeled off that living insects were found. It is evident, there- 

 fore, that in such cases a second application is necessary. It is 

 important to note also that the trees thus treated had not apparently 

 suffered any ill-effects from the wash, so that its use may be recom- 

 mended with safety. It is doubtful, however, if such a wash will prove 

 equally effective on other trees, as it must be borne in mind that the 

 young Castilloa trees are covered with hairs to which the lime readily 

 and more or less permanently adheres, so that it covers the scale insects, 

 at any rate for a sufficiently long period to prevent the young escaping 

 from beneath the shield-like covering or from the eggs which may not 

 be destroyed by the application. It is obviously necessary also that 

 the boles of the Immortelles should also be treated with some kind of 

 wash, and for these trees the writer would recommend the lime and 

 sulphur wash, which for smooth-barked trees is much more effectual 

 than' the lime and salt, though two sprayings or dressings may be found 

 necessary. 



As a means of prevention, seedling plants should be very carefully 

 examined for such pests, and if found to harbour them should be 

 discarded altogether or subjected to treatment wfth hydrocyanic acid 

 gas before they are removed from the nurseries. The safest course, 

 as well as the most economical one, is to refuse absolutely to accept 

 nursery stock unless it is perfectly clean and free from such pests. 



