METHODS OF PREVENTION AND REMEDIES. 51 



has to be taken into the body before it becomes effec- 

 tive, is of no use against " scale " and " mealy bug," or 

 aphides, or any insect which lives by suction. 



In this country there is no organised system of pre- 

 vention against the introduction of insect pests, which, 

 to say the least of it, is a very unsatisfactory state of 

 affairs, resulting only too frequently in the introduc- 

 tion of new Coccids from all quarters of the globe. 

 As instances of such introduction I may mention the 

 following species, which, with two exceptions, have 

 thoroughly established themselves in this country : 



Aspidiotus alienus, Newstead. Discovered in 1889 

 by Mr. E. E. Green. 



Diaspis (Aulacaspis) pentagona, Targ.-Tozz. Im- 

 ported from Japan in 1898. 



Mytilaspis citricola, Packard. Common on imported 

 oranges and lemons, and quite recently on cultivated 

 plants. 



Ischnaspis filiformis, Douglas. Discovered in 1887, 

 when Mr. Douglas first described it. It occurs now in 

 many places as a greenhouse pest. 



Gymnaspis aechmece, Newstead. Quite a recent in- 

 troduction. It is now well established and increasing. 



Fiorinia fioriniae, Targioni-Tozzetti. A pest on palms 

 in many districts. 



F. Keivensis, Newstead. Quite recently discovered. 



Pinnaspis pandani, Comstock. Chiefly a palm pest, 

 and very destructive. 



Orthesia insignis, Douglas. Steadily increasing, and 

 extending into fresh districts. 



leery a segyptiacum, Douglas. The plants upon which 

 this species was imported were all destroyed, and no 

 trace of the insects have since been found. 



Thus within the last twelve years we have seen the 

 introduction of at least ten species of Coccids, of 

 which Orthesia insignis may prove as injurious to our 

 cultivated plants as our common " mealy bugs " (Dae- 

 tylopins, spp.), and it is much more difficult to destroy 

 than the latter. It needs, therefore, no further com- 



