364 POPULAR SCIENCE MONTHLY 



The Use of Novius Cardinalis against Icerya 



Icerya purchasi and Novius cardinalis in America. — Icerya purchasi 

 is a scale insect Hying upon different trees and particularly upon citrus 

 trees. It is originally from Australia, and was accidentally introduced, 

 about 1868, into California where it did enormous damage, and 

 threatened to ruin the cultivation of oranges and lemons. All attempts 

 to fight this Australian insect with different insecticides were vain. It 

 continued to spread in a progressive manner from the orchards that had 

 already been annihilated or were in bad condition. 



Eiley, then director of the Division of Entomology of the Depart- 

 ment of Agriculture, at Washington, thought of utilizing the natural 

 enemies of the scale insect. Ascertaining that in Australia, its original 

 home, it did not seem to be seriously injurious, and to be without im- 

 portance from the economic point of view, he was led to think that it 

 probably was held in check there by parasites. Investigations which he 

 made on this question having confirmed his ideas, he made every effort 

 to accomplish the desired end, namely, the acclimatization of the natural 

 enemies of Icerya in California. Finally, after numerous appeals to 

 the government, he was able to arrange for a sending of two agents 

 of the Division of Entomology to Australia on the occasion of the 

 exposition at Melbourne, in 1888, with a credit of $2,000. One of these 

 agents, Mr. Koebele, was especially instructed to search for parasites of 

 Icerya. 



On his return he brought a collection of the natural enemies of the 

 Australian scale insect. Among these there were a hundred living 

 specimens of Novius cardinalis. It multiplied so rapidly that in the 

 following year, 1889, they could distribute to the fruit growers of Cali- 

 fornia 10,000 specimens. A year and a half after its introduction it 

 had relieved the region from Icerya, and had reduced their number to 

 a practically negligible quantity. According to witnesses this deliver- 

 ance possessed for the inhabitants of the country an almost miraculous 

 character. Immense groves of oranges bearing no fruit, covered with 

 a horrible, white leprosy composed of the Iceryas, and which seemed 

 irremediably lost, suddenly took on a new vigor and furnished abun- 

 dant crops. Now the only natural means necessary to hold Icerya in 

 check consist in sending a small number of Novius cardinalis to start 

 colonies in the district where the scale insect shows a tendency to 

 regain its foothold. In this way reserves of Novius are constantly 

 kept on hand for exportation, either to the different districts of the 

 State of California or to foreign countries, and the State Board of 

 Horticulture of California has constructed small boxes of glass and 

 wire gauze of octagonal form, 16 feet in diameter and 18 feet high, 

 allowing the Iceryas and the Novius to live upon the trees surrounded 

 in this way. 



