Introductory. 5 



prey, which is unable to escape or to make any movement. Un- 

 fortunately, our native Lady-birds have enemies of their own, and 

 are consequently greatly handicapped in their good work. But 

 grand results have followed, in other countries, the introduction of 

 a foreign beetle which, having left its own enemies behind, finds 

 itself free to increase without check so long as suitable food is 

 forthcoming. The introduction of the ' Vedalia beetle ' into Cali- 

 fornia is a well-known case in question, resulting as it did in the 

 complete clearance of the dreaded ' Fluted Scale' {Icerya purchasi) 

 from the orange plantations of that country. 



Another useful friend to the planter is the larva of a species of 

 'Lace-wing' fly. This little animal is provided with long sickle- 

 shaped jaws, hollow and perforated at their tips, which it plunges 

 into the body of its victim and through which it sucks up the juices 

 of the unfortunate insect, whose empty skin is then fastened upon 

 the back of the devourer together with those of former sufferers. 



The caterpillars of butterflies and moths are usually themselves 

 vegetable feeders, and often very injurious to plants. But we have 

 in Ceylon at least one of each class that has developed carnivorous 

 tastes and adopted a diet of Scale Insects. The larva of a small 

 blackish butterfly {Spalgis epius) feeds entirely upon Mealy-bugs ; 

 and that of a small noctuid moth {Eitblejiima coccidiphaga, Hampsn), 

 preys upon several kinds of Scale-bugs, forming a neat covering 

 for its body out of their empty scales. 



The internal feeders are the hymenopterous parasites — that 

 vast army of minute wasp-like insects (belonging chiefly to the 

 CJialcididcE), that insinuate their eggs into and pass their earlier 

 stages within the bodies of their victims. Their small size may be 

 realised when we find that four or five of these little wasps may be 

 developing simultaneously within the body of a Scale Insect less 

 than one eighth of an inch in length. The presence of one or 

 more of these parasites does not always seem to deprive the insect 

 of its reproductive powers; but such diseased individuals cannot 

 be so prolific as healthier insects, and many of them are certainly 

 killed off before attaining the adult stage. I have sometimes 

 found a colony of Scale-bugs in which nearly every individual had 

 been parasitised. 



It was at one time supposed by planters that the ants which 

 are so constantly in attendance upon Scale-bugs were preying 

 upon them, and the formidable ' Red-ant' {CEcopIiylla sniaragdind) 

 was actually imported into some estates with the view of exter- 



