ARTIFICIAL BREEDING OF PARASITES. 17 
Professor tiiley in his 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 
has, however, been furnished by Professor Riley since these pages were prepared for 
the printer, and as it refers to an insect very destructive 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 on " the artificial importation 
and colonization of parasites and predac eous enemies of injurious insects" : 
"The eucouragemeut 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 in point are not uncommon. * * * 
" But this intentional distribution of the parasites or natural enemies of an injurious 
insect from one part to another of its native couutry 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 present note is to cite an 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 the case of Microgaster glomeratus, which, after 
several futile efforts, was introduced from Europe and established in the United States 
in 1885, and which has now become 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 rapce, 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 become a 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 pernicious scale insect (Icerya purchasi 
Maskell). ThiB is one of our largest coccids and, from its habits and characteristics, 
very difficult to overcome. It does a great deal of damage — not only 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, in 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 only the most important of the parasites, 
an interesting Dipteron (Lestoplionus iceryce Williston), but also several predaceous 
species, and particularly certain ladybirds (Coccinellidse.) 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 the 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&re multiplying and spreading in a most satisfactory manner. The consign- 
5 ENT 2 
