though but some fifty odd species of scale insects were hitherto 

 recorded from these Islands, a number of others have since been 

 discovered and one may safely estimate the number of scale in- 

 sect species on these Islands to be in the neighborhood of one 

 hundred. Some of these are comparatively rare, others are too in- 

 conspicuous to be noticed by the casual observer; while a largje 

 number of them are so w^ell kept in check by the perdaceous and 

 parasitic insects introduced by Mr. Koebele, in course of his work 

 here, that while colonies of them may be found here and there,, 

 their injury is insignificant. But we still have a few species,, 

 such as the Purple scale above referred to, which are not kept in 

 check effectively by the enemies praying upon them and which 

 find the environment satisfactory for rapid multiplication. The 

 amount of damage that they inflict cannot adequately be esti- 

 mated for the reason that the plants they attack are only to a ver^r 

 limited extent cultivated on a commercial basis. Yet nearly every 

 door yard, urban or suburban, has its citrus trees, avocado pear 

 trees, guava, etc., and the owners of these know the bhghting ef- 

 fects of the scales infesting these trees. Indeed, one observes 

 many plants with leaves crumpled up and mis-shapen, the effects 

 of colonies of scale insects ultimately destroyed by lady-birds, and 

 wonders if it were not in wisdom's course to have mechanically, 

 as by means of a soap wash, killed outright the infesting scales 

 and thus prevented the unsightly appearance, to say nothing of 

 the damage. 



Unless every single species injuring a plant is taken care of 

 by natural enemies, if the plant is to be saved from destruction, 

 artificial remedies become inevitable sooner or later. And when 

 the application of the remedy is made it is bound to affect practic- 

 ally every form of life upon the treated plant, anyway. Wanton 

 destruction of beneficial insects shows poor knowledge and judg- 

 ment, and is wrong, but the occasional killing of a beneficial in- 

 sect in course of a useful and necessary application is decidedly 

 pardonable. 



Let us take for illustration an orangie tree. Following is a 

 list of insects that-aft'ect it and their natural enemies: 



Pests. Their effective enemies. 



Purple scale Practically none. 



Mealybugs Lady-birds {Cryptolacums). 



Aphis or plant lice Lady-birds. 



Florida red scale {Chr. ficus) Practically none. 



