October. '15] SWEZEY: INSECTS IN THE HAWAIIAN ISLANDS 



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native home of a pest and making a study of its natural enemies for 

 the purpose of introducing them to the countries where the insect has 

 become established as a pest. 



Considering its size, Hawaii has probably accomplished more in the 

 way of combating insect pests by the introduction of their natural 

 enemies than has any other country. The first introduction of benefi- 

 cial insects in Hawaii was when, following his remarkable success in 

 the introduction of an Australian lady-beetle {Novius cardinalis) into 

 California to destroy the cottony cushion scale, Mr. Albert Koebele 

 also introduced it here, where it soon reduced the same pest to such 

 scarcity that it is no more a menace to the trees and plants previously 

 affected. A few are to be seen now and then on various plants and 

 trees, but the lady-beetle is in such control that no serious infestations 

 now occur. 



This introduction was as early as 1890, and shortly after, in 1893, 

 Mr. Koebele was engaged by Hawaii to continue this work of finding 

 and introducing beneficial insects. Many of the first successful intro- 

 ductions were lady-beetles. About a dozen different species were 

 successfully introduced by 1896, mostly from Australia and the Orient. 

 Among these were Cryptolcemus montrouzieri, Rhizohius ventralis and 

 Rhizohius toowoomhce which feed on various species of mealybugs; 

 Coelophora inequalis, Platyomus lividigaster, Scymnus loewii and Scymnus 

 notescens feeding on plant-lice; Orcus chalyhoeus and Chilocorus circum- 

 datvs feeding on scale insects. Many other lady-beetles have been 

 tried, but not all were successful. Some failed to become established, 

 and others, although established, failed to increase sufficiently as to 

 be of noticeable use. However, the combined work of all mentioned 

 above has reduced greatly such pests as mealybugs, scale insects and 

 plant-lice. 



Thirty or more species of hymenopterous parasites have been intro- 

 duced, also, to prey on this class of insect pests. The lady-beetles 

 are often seen busily feeding upon their respective hosts and the general 

 public recognizes them as beneficial; but the parasites, often very 

 minute, are seldom seen, and hence their usefulness is not generally 

 known by people unfamiliar with their habits. Their presence may 

 be determined by close examination and finding the tiny round holes 

 which they have gnawed in the scale insects, in emerging from them, 

 after completing their transformation in the place where they have 

 been feeding on the living bug, or its eggs, beneath the scale. These 

 scales with the tiny holes may often be found in great abundance on 

 scale-infested plants, mute evidence of the usefulness of the parasites. 



Among the most valuable of the introduced Coccid parasites are: 

 Encyrtus fuscus, Blepyrus marsdeni, Microterys flavus, Apentelicus 



