1919?, 12? 



INSECTS AFFECTING THE AVOCADO IN 

 TRINIDAD AND TOBAGO. 



By F. W. Urich, 

 Entomologist, Board of Agriculture. 



The full grown avocado tree is fairly free from insect pests and 

 only occasionally suffers from scale insects with the resulting black 

 blight and from the webbing caterpillars ; in the early stages of its 

 growth the avocado is more likely to suffer from insect pests and the 

 seedling, the recently budded plant and the young tree cut back to form 

 low branches should always be carefully examined for the first appearance 

 of insect pests. During the dry season scale insects are under favourable 

 conditions for increase and at the opening of the rainy season cater- 

 pillars may occur in numbers. 



ANTS. 



The stinging ant {Soleno-psis cjeminaid) is a serious pest to young 

 plants not only does it encourage and protect all kinds of mealy bugs 

 and scale insects but it will also bite off young bark from shoots and 

 stems of the trees. In bad attacks fairly large branches can be entirely 

 destroyed. Stinging ants can be controlled by destroying the nests with 

 carbon bisulphide and cyanide of potassium or sodium. 



The carbon bisulphide treatment is too well known to require descrip- 

 tion. Cyanide of potassium is also effective. For use take one ounce of 

 the salt and dissolve it in one gallon of water : pour the solution into the 

 nest until the ground is saturated. When using cyanide bear in mind 

 that it is a deadly poison. Carbon bisulphide and cyanide will kill 

 plants when the roots are touched. Other treatments are boiling water 

 and puddling when nests are not situated in masonry. If a little resin 

 wash is added to the boiling water it will make the treatment far more 

 effective. When on the roots and stems of plants they can be sprayed 

 with resin wash and nicotine, but frequent applications may be 

 required as they return very soon from neighbouring nests. Trees can 

 be protected by banding the stems and trunks with tree tanglefoot see 

 formula ] , 2 and 3. Napthalene flakes dusted around a plant will keep 

 away ants for a few days. 



Another species of ant found on the avocado tree is the acrobat ant, 



{Creynastog aster hrevispinosa) which is not as bad as the stinging ant as- 



it confines itself to the care of scale insects and mealy bugs and does 



not gnaw the bark of the tree. It makes its nest under loose dried 



bark and in rotten wood resulting from badly dressed pruning wounds or 



from dead branches left on the trees. Nests should be cut out as much 



as possible and the place painted over with crude oil or strong resin 



wash. 



SCALE INSECTS AND MEALY BUGS. 



The following scale insects and mexly bugs are found on avocado : — 



1. Pulvinaria pyriformis. 



2. Aspidiotus destructor. 



3. Saissetia nigra. 



4. Pseudococcus nipcB. 

 5. Pseudococcus citri. 



Pulvinaria pyriformis is the most common of above and there 

 is hardly an avocado tree that is entirely free from it. In severe 

 infestations it causes black blight. 



