30 



THE WORK AGAINST ICERYA PURCHASI IN PORTUGAL, WITH AN 



ACCOUNT OP THE INTRODUCTION FROM AMERICA OF 



NOVIUS CARDINALIS. 



By L. O. Howard. 



In several of the previous bulletins of this Division mention has 

 been made of the occurrence of the white or fluted scale (Icerya pur- 

 chasi) in disastrous numbers in the orange and lemon groves along the 

 banks of the river Tagus in Portugal. This insect, which reached 

 Portugal some years ago probably from her colonies in the Azores, to 

 which point it was probably introduced many years previously from 

 Australia upon acacias grown as wind-breaks for the orange planta- 

 tions, has attracted the attention of the Portuguese Government by its 

 damage during the last two years. Senhor Alfredo Carlos Le Cocq, of 

 the department of agriculture of Portugal, has published a number of 

 communications upon this insect in the "Archivo Eural, Gazeta Dos 

 Lavradores,*' and in the numbers of this journal for December 28, 1897, 

 and June 28, 1898, gives excellent summaries of the spread of the 

 insect, the work which has been done against it, and especially of the 

 results of the attempts which have been made through the U. S. 

 Department of Agriculture, aided by the State Board of Horticulture 

 of California, to introduce and acclimatize the Australian predatory 

 enemies of the scale. In the article first mentioned is given an account 

 of the spread of the scale in the district of Lisbon. In and about the 

 city of Lisbon nearly all of the private and public gardens and nur- 

 series are infested and the insect is found in thirty-two other localities. 

 Prior to the attempt to introduce natural enemies of the insect exten- 

 sive experiments with washes were carried on under the direction of 

 the Chemical-Agricultural Station of Lisbon. After much experimen- 

 tation it was determined that an emulsion of bisulphide of carbon with 

 soapsuds was the most rapid and effective of all. The formula used is 

 as follows : 



Black potash soap kilograms . . 1. 5 



Warm water liters.. 10 



Bisulphide of carbon do . . 3 to 4 



Cold water do 90 



The soap is dissolved in the warm water and when the solution cools the bisul- 

 phide is gradually added, agitating it constantly to make the emulsion homogeneous, 

 the latter being finally diluted with the cold water, care being taken to stir well 

 before using. 



It is reported that there is no inconvenience in preparing sufficient 

 quantities for one or two days' use, but it appears that the emulsion 

 prepared the evening before using is more energetic, from which we 

 judge that there is a gradual evaporation of the bisulphide from the 

 emulsion. There is some danger of the pump rusting as the result of 

 the action of the bisulphide, and it should be washed out with water 

 several times after use and wiped dry. Moreover, only vulcanized rub- 



