Introductory. 3 



or molestation, until native parasites and predacious insects and 

 animals acquire the habit of preying upon them. By the intro- 

 duction of some of their enemies in the land from which they came, 

 man can in exceptional cases do much towards counteracting their 

 increase, but in the vast majority of cases generations are required 

 before a proper balance becomes again established.' 



As some little set-off against the destructiveness of many of 

 the Scale Insects, a few species may be quoted that are of economic 

 use. The well-known Cochineal insect {^Coccus cacti), producing 

 the red colouring matter known as Cochineal, is a case in point. 

 Another species {TacJiardia laced), secretes a resinous substance 

 from which is made the ' lac ' or ' shellac ' of commerce, while from 

 the insect itself is prepared the fine crimson pigment known as 

 ' lake.' Ericerus pela, a Chinese insect, secretes copiously a waxy 

 matter that is used in the manufacture of candles in that country. 



We have in Ceylon representatives of all these types. A 

 Cochineal insect, identical with or closely allied to the Coccus cacti, 

 breeds upon the wild cactus plant {Opuntia Dillenii) ; but I do not 

 know if it has ever been locally utilised or cultivated. There are 

 two species of Tachardia producing ' lac,' the product of which is 

 collected by the natives and used in the manufacture of varnishes. 

 Ccroplastes ceriferus is an abundant producer of insect wax, but 

 the quality is said to be unsuitable for economic purposes. 



The absence of any winter or resting stage for plant life in 

 Ceylon allows of the continuous activity of insect pests. In coun- 

 tries where a dead season prevails for a part of the year the Scale 

 Insects produce only a limited number of broods, varying in 

 different species, before the fall of leaf and cessation of the flow 

 of sap compels them to cease their depredations. The greater 

 number of the insects die off, while the balance pass the winter 

 either in a dormant state or in the ^^^ stage. They are now 

 subject to many dangers that tend to still further reduce their 

 numbers. The bareness of the branches lays them open to attack 

 from insectivorous birds that pry into every crank and cranny in 

 search of their accustomed food. Abnormal wet or frosts will pick 

 off the more exposed individuals, and but a comparatively small 

 number will survive to continue the species. Hence, in England, 

 we seldom if ever hear of any such serious plagues as occur in 

 more southern countries. In Ceylon, however, where perpetual 

 summer reigns, an endless succession of broods follows one upon 

 another, only partially checked by the season of heavy rains. In 



