1(V2 



LEGISLATION AND [MFOBTED PLANTS. Many insects 

 which have developed into pests <>l' first importance have 

 done so in countries or localities into which t hev have been 

 introduced. The admission ol' such pests has generally been 



in connexion with imported plants. The insects most liable 

 to he brought in by this means are probably scale insects and 

 white fly ; but many others have been known to be intro- 

 duced in this wa}^. Insects which live as borers, or within 

 the tissues of plants in any way, may easily lie trans- 

 ported and become established under new conditions. Grain 

 and seeds also easily harbour insects, and provide for their 

 introduction to new localities. 



In order to provide against the introduction of insect 

 pests in this way, legislation has been enacted in all 

 the West Indian islands, making it possible for the 

 Governor of each Colony to prescribe the conditions 

 under which plant material of all kinds intended 

 for propagation may be imported. The total prohi- 

 bition of the importation of all such plant material 

 from any country where diseases and pests are 

 known to occur, which it may be deemed impossible to 

 destroy on imported plants, may be ordered ; while it is 

 provided that all plant material intended for propagation 

 shall be disinfected in such manner as the officer responsible 

 for this work shall decide to be the most suitable. 



Fumigation with hydrocyanic acid gas and carbon 

 bisulphide, and disinfection by means of Bordeaux mixture, 

 are the methods most frequently prescribed. In Barbados, 

 cotton seed imported for the manufacture of cotton seed oil 

 is fumigated with sulphur dioxide. 



Remedial Measures. 



INSECTICIDES. These may be divided into four general 

 groups : stomach poisons, contact poisons, fumigants and 

 repellents. 



Stomach poisons are those substances which are used 

 in such a manner that they will be eaten by the insect, and 

 taken into the digestive system. It will be seen that such 

 poisons are useful only in the case of insects which bite off, 

 and swallow, particles of food to which poison may be 

 applied or of those which, having sucking mouth parts, will 

 take an artificial food to which a stomach poison has been 

 added. 



