4 o8 POPULAR SCIENCE MONTHLY 



the world of a practitioner, launched by his government into the search 

 for the parasites of a fly, it is to show the vogue which the use of bene- 

 ficial insects in the struggle against injurious insects enjoys in certain 

 countries. 



What will be the result of this experience? It is premature to 

 express an opinion on the subject. The time necessary for the definite 

 acclimatization of a parasite, and above all for it to multiply sufficiently 

 to restrain the insect which it is its mission to attack, must be extremely 

 variable, according to the species and also according to the extent of 

 spread of the plague. It is only necessary for some months to elapse 

 in the case of Novius cardinalis, but years may be necessary for such 

 parasites as the Ichneumonids. 



Utilization of Beneficial Insects in the Hawaiian Islands. — Journeys 

 of Koebele. — The method of which we are speaking has nowhere been 

 applied in a more extensive way than in Hawaii. These islands, ever 

 fertile, present, as is well known, a climate extremely favorable for 

 large number of tropical and subtropical crops. At the beginning 

 of the American colonization, the only plants of economic importance 

 were yams and cocoanuts, but since that time enormous numbers of 

 useful plants, coming from all parts of the world, have been acclimat- 

 ized in this rich country, and with them also have unfortunately been 

 imported a large number of their natural enemies, among them, and 

 the most important, scale insects and plant lice. It has been stated 

 that the Hawaiian Islands are the paradise of these insects, since they 

 are represented by numerous species coming from all parts of the world, 

 which prosper there and flourish. 



After having seen, in 1890, their orange and lemon trees relieved 

 from Icerya by Novius cardinalis, the planters directed their efforts to 

 this method in order to combat other agricultural plagues, and par- 

 ticularly the enemies of coffee and sugar cane. 



They, therefore, gave Mr. Albert Koebele a commission to under- 

 take this work. This entomologist, celebrated for his discovery of 

 Novius cardinalis, and already employed at the same time by the State 

 Board of Horticulture of California upon a similar mission, commenced 

 by sending from California the Coccinellids which seemed most de- 

 sirable for Hawaii, notably : Hyperaspis undulata Say, Scymnus debilis 

 Lee, Chilocorus bivulnerus Muls., Rhizobius ventralis Er., and R. 

 Iophanto3 Blaisd. The two latter became naturalized and constituted 

 a useful resource for the country. 



In 1893 he visited the islands and left immediately for Australia. 

 From 1894 to 1896 he journeyed through Australia, China, Ceylon 

 and Japan, and made during this journey numerous sendings of this 

 insect to Hawaii and California. Among the best of these must be 

 mentioned, in the first place, Cryptolo3mus montrouzieri Muls., orig- 



