ARTIFICIAL BREEDING OF PARASITES. 17 



Professor tviley iu bis third and subsequent Missouri reports has 

 shown how easily and practically certain parasites of the Plum Cur- 

 culio and of various scale-insects may be artificially disseminated, and 

 has successfully introduced the most common European parasite {Apan- 

 teles glomeratus) of the imported cabbage worm.* 



* The most strikiug illustration of the good that may be accomplished by this means 

 bas, however, been furnished by Professor Riley since these pages were prepared for 

 the printer, and as it refers to an insect very destructi%'e to forest as well as fruit 

 trees, we reproduce here the paper read by him at the Toronto (1889) meeting of the 

 American Association for the Advancement of Science ou " the artificial importation 

 and colonization of parasites and predac eous enemies of injurious insects" : 



"The encouragement of the natural checks to the increase of insects injurious to 

 vegetation may be of a two-fold nature. It frequently happens that an indigenous 

 species is found to have certain parasites in only a portion of the country which it 

 inhabits. In such cases, where it is practicable to transport the parasites, a great 

 deal of good may be accomplished. Cases iu point are not uncommon. * » * 



" But this iutentioual distribution of the parasites ornatural enemies of an injurious 

 insect from one i»art to another of its native country is by no means to be compared 

 in importance with the introduction of such parasites or enemies from one country to 

 another, in which the injurious species has obtained a foothold, without the corres- 

 ponding natural enemies which serve to keep it in check in its original home. 



" The object of the prestot note is to cite au illustration of artificial introduction on 

 a large scale, which has already been productive of great good. A successful attempt 

 of this kind had been made by me in tiie case of Microgasier (/lomerafiis, which, after 

 several futile efiorts, was introduced from Europe and established in the United States 

 in 1885, and which has now becomti so widely distributed as to raise the question of 

 its previous existence there. This Microgaster is one of the commonest parasites of 

 the European Cabbage Worm, Pieris rapa', which got a foothold in America, without 

 its European enemies, about the year 1859, and which rapidly spread over the States 

 and parts of Canada, with disastrous results to the cabbage crop. 



" The case to which I would particularly allude is, however, far more important and 

 satisfactory. Orange culture has becomea very important industry in southern Cali- 

 fornia. The orange groves there have suffered for some years from the attacks of 

 several insects, but particularly of a very peruicious scale insect (Icerya purchasi 

 Maskell). This is one of our largest coccids and, from its habits and characteristics, 

 very difficult to overcome. It does a great deal of damage — not onlj^ to the orange 

 and other citrous fruit-trees but to many other cultivated plants and to forest trees. 

 The damage has become so serious during the past few years that many orange- 

 growers have abandoned their groves, while the cost and trouble of protecting these 

 by the use of insecticides have always been great, even where successful. After 

 careful researches I ascertained that the insect was without much question a native of 

 Australia and had been artificially introduced not only into southern California, but 

 also into Cape Colony, iu South Africa, and probably into New Zealand ; also that in 

 its native home it rarely did serious damage, being kept in check there by various 

 natural enemies and parasites. Some attempt was made, through correspondence 

 with Mr. Frazer S. Crawford, of Adelaide, to introduce one of the parasites by mail 

 in 1887. Specimens were received alive and liberated at Los Angeles under confine- 

 ment, but no positive evidence was obtained of multiplication or colonization. Spe- 

 cial effort and introduction on a larger scale seemed necessary. 



"Last autumn and winter in connection with the commission appointed to visit the 

 Melbourne International Exposition and through the State Department I was able to 

 send one of my field agents, Mr. Albert Koebele, to Australia with instructions to study 

 these natural enemies and to send living specimens to California. The principal facts 

 have been recorded in my last annual report as entomologist of the United States 

 Department of Agriculture and in late numbers of "Insect Life," a monthly bulletin 

 published under the auspices of the entomologist and his assistants. Without going 

 into detail I may say that Mr. Koebele's mission has been eminently successful and that 

 we have succeeded in introducing alive not onlythe most important of the parasites, 

 an interesting Dipteron {Lesioplionus iceryw Williston), but also several predaceous 

 species, and particularly certain ladybirds (Coccinellidje.) These were brought over 

 last winter and spring, have become well acclimated, and are now spreading and 

 multiplying at a rapid rate. The latest reports which I have received from California 

 are to tlie effect that one of the commoner ladybirds but recently described, namely, 

 the Vedalia cardinalis, and another lately described by Dr. D. Sharp as Scymnus res- 

 titutor are multiplying and spreading in a most satisfactory manner. The cousign- 



5 ENT 2 



