133 



one place to another in their undeveloped or adolescent stages.* Le 

 Baron, in his studies of the Oyster-shell Bark-Louse of the Apple and one 

 of its parasites (Aplielinus mytilaspidis), transported scale-covered twigs 

 during winter from Geneva, 111., to Galena, 111., with beneficial results. 

 The experiment was conducted on a small scale, but the parasites 

 issued and became domiciled in t*heir new locality, thus proving the 

 practicability of his scheme. In neither my own experiments nor in Le 

 Baron's, however, was sufficiently thorough examination made to prove 

 that the parasites did not already exist in the localities in which they 

 were colonized. 



Planchon and myself introduced Tyroglyphus phylloxerce from America 

 into France in 1873,t and it became fully established, as subsequent 

 correspondence and observation showed. In 1874 efforts were made 

 to send over from England to New Zealand certain Aphid parasites to 

 check the alarming increase of those plant pests there, and while I have 

 no records at hand to show with what success, the later successful intro- 

 duction of bumblebees to the latter country to fertilize the red clover 

 is well-known history. In his report upon the parasites of Coecida3 in 

 the Annual Keport of the Department of Agriculture for 1880, Mr. 

 Howard gave the subject some theoretical attention and elaborated 

 upon the ease with which Coccid parasites could be transported from 

 one part of the country to another during winter. He suggested the 

 experiment of transporting Dilophogaster calif ornica from the Pacific 

 coast to certain of the Southeastern States, where it might be expected to 

 prey upon certain large species of Lecanium. In 1883, after previous 

 futile attempts by myself and Mr. Otto Lugger, and with the assistance 

 of G. C. Bignell, esq., of Plymouth, England, the living cocoons of 

 Microgaster glomeratus, a common European parasite of Pieris rapce, 

 were successfully imported by the Department and the colonization of 

 the species was established, not only in the District of Columbia, but 

 in Iowa, Nebraska, and Missouri, as specimens were simultaneously 

 sent to the agents of the Division in those States.f It has become 

 so widely distributed since then as to lead to the inference that 

 it must have been previously introduced at some other points, though 

 the spread of an introduced species, even when introduced at a single 

 point, is often so rapid that it surprises us, especially of a species 

 that is winged, as evidenced by the spread of the Horn Fly (Hcemato- 

 Ma serrata) over the whole eastern United States in about four years. 

 Later, in 1891, with the aid of Mr. Fred. Enock, of London, a success- 

 ful effort was made to introduce into this country from England an 

 important Chalcid parasite of the Hessian Fly, Entedon epigonus Walker 

 (Semiotellus nigripes Lind.). The details of this experiment will be 



*Tliird Rep., Ins. Mo., 1870, p. 29; Fifth Rep., do., 1873, p. 90. 



t Sixth Report, Ins. Mo., 1874, p. 55. 



t Report of the Etomologist in Rep. U. S. Dept. Agric. for 1884, p. 323. 



