362 ANNUAL REPOET SMITHSONIAN INSTITUTION, 19 3 2 



time the Italian entomologist, Silvestri, had visited Malaya and 

 reported finding several very eifective parasites. These species were 

 imported into Cuba during 1930 and 1931 and one of them, Eretmo- 

 ceriLs serius, has been remarkably effective. The liberation of a few 

 hundred individuals in an infested grove results in effective and 

 complete control in 6 to 10 months. This parasite has been estab- 

 lished in the other islands of the West Indies and in Central America, 

 and in all localities has proved equally successful. As a result of 

 this work, the citrus growers of the Gulf coast now have little to 

 fear from the black fly. The possibility of its entry is greatly 

 reduced, and should it appear in this country, the parasites can be 

 quickly established here. 



An equally successful result has recently been achieved in Cali- 

 fornia in the effort by the college of agriculture and the experiment 

 station to control the so-called citrophilus mealybug upon citrus. 

 This species, like the cottony-cushion scale, evidently came originally 

 from Australia. Its parasites were found and liberated in California, 

 and within two years the pest was completely subjugated. 



In Hawaii we find an exceptional illustration of the extent to 

 which parasites may be utilized in controlling insects injurious to 

 crops. The sugarcane growers in the islands maintain their own 

 experiment station, which deals with all problems relating to sugar 

 production. During the past 30 years at least five major insect pests 

 of sugarcane have been effectively controlled by the introduction of 

 parasites from various islands of the South Pacific and from Asia. 

 In addition, the injuriousness of manj^ other species has been 

 markedly reduced. 



The more frequent successes in Hawaii along this line as com- 

 pared to those in the United States are due to several factors. The 

 Hawaiian Islands are of volcanic origin and consequently all plant 

 and animal life has been introduced. Their insect fauna is conse- 

 quently quite simple, and the number of species is not great. There 

 is less likelihood of the loss of an introduced parasite species through 

 dispersion or by its transfer to another host. Climatic conditions 

 ure ideal throughout the year and are quite similar to those which 

 exist in other Pacific islands. The introduced species consequently 

 do not have to adapt themselves to a changed or a complex environ- 

 ment. 



In many parts of the world an extended attempt is now being 

 made to utilize these insect enemies of their own kind to prevent 

 serious damage to agricultural crops. While they are often obscure, 

 and their attack upon the plant-feeding species is seldom noticed by 

 the grower, yet without them the economical production of practi- 

 cally all crops would be rendered much more difficult. 



