450 



JOURNAL OF ECONOMIC ENTOMOLOGY 



[Vol. 8 



THE WOOLLY APHIS AS A PEAR PEST 



By G. P. Weldon, Sacramento, Col. 

 {Withdrawn for -publication elsewhere.) 



Vice-President Cooley: The next paper will be read hy Mr. 

 O. H. Swezey. 



SOME RESULTS OF THE INTRODUCTION OF BENEFICIAL 

 INSECTS IN THE HAWAIIAN ISLANDS 



By Otto H. Swezey, 



Entomologist, Experiment Station of the Hawaiian Sugar Planter's Association, 



Honolulu, Hawaii 



Only a very few of the native insects of the Hawaiian Islands have 

 become injurious to cultivated crops or plants. The insect pests 

 occurring there are in most cases foreign insects that have arrived 

 through the channels of commerce. The promiscuous importation of 

 fruits, seeds, trees, plants, etc., from all parts of the world has been 

 the ehief way by which the numerous insect pests have gained access 

 to these islands. One has but to observe the profusion and variety 

 of trees, shrubs, and plants in the public parks and private grounds 

 of Honolulu to realize to what extent this has been carried on, for in 

 all of this there is only an occasional native tree or plant to be seen. 



The most of this introduction of trees and plants was done before 

 the present rigid system of plant inspection and quarantine against 

 insect pests was instituted, and the insects have come along freely with 

 their host plants. There are about seventy-five species of scale insects 

 known in the islands, none of which are native, but all have been 

 brought in in this way. The sugar cane leaf-hopper, too, so well 

 known from its having caused such heavy loss to the sugar industry, 

 is a striking example of a pest arriving with its host plant, coming in 

 as it undoubtedly did in the egg stage in importations of cane cuttings 

 for planting. 



Many insects have arrived in other ways through the channels of 

 commerce, as in packing, in soil about the roots of plants, along with 

 domestic animals, chance travellers on board vessels, etc. Some, not 

 pests in their home country, have become pests here when established 

 in the absence of their natural enemies. Observations on this line 

 have led to the practice which is now so prevalent of searching for the 



