PARASITIC AND PREDACEOUS INSECTS. 679 



are mucli affected by parasites, and neither of which can survive 

 if the cases are plucked in winter and placed away from any trees 

 or shrubs, while under these circumstances the parasites will per- 

 fect and escape. 



It is quite different with the second method of dealing with 

 beneficial insects which I have mentioned, for here man has an 

 opportunity of doing some very effective work. It is only within 

 comparatively recent years that the importance of this particular 

 phase of the subject has been fully realized. Various more or 

 less successful efforts have also been made, and the transmission 

 from one place to another of certain parasites of the plum cur- 

 culio ; of certain parasites of the common oyster-shell bark-louse 

 of the apple ; the successful colonization in France of a certain 

 mite which attacks the grape phylloxera ; the efforts to send 

 parasites of plant-lice from Europe to Australia ; the introduction 

 into this country of Microgaster glomeratus, a common European 

 parasite of the cabbage worm, and of Entedon epigonus, a com- 

 mon European parasite of the Hessian fly are matters of record 

 in State and Government publications. 



In 1887 and 1888 the now well-known importation of Vedalia 

 cardinalis from Australia and New Zealand to California to prey 

 upon Icerya purchasi was successfully carried' out. The history 

 of this striking example of the beneficial results that may in ex- 

 ceptional cases flow from intelligent effort in this direction is 

 now sufficiently well known to American economic entomologists, 

 but anticipating that we shall have foreign delegates among us, 

 and that our proceedings will be published more widely than 

 usual, it will perhaps be wise to give the salient historical facts 

 in the case, even at the risk of some repetition of what has been 

 already published. 



The fluted scale, otherwise known as the white or cottony- 

 cushion scale (Icerya purchasi Maskell), is one of the largest spe- 

 cies of its family, and up to 1883 had done immense injury to 

 the orange groves and to many other trees and shrubs of south- 

 ern California. From Australia, its original home, it had been 

 imported into New Zealand, South Africa, and California the 

 evidence pointing to its introduction into California about 1868, 

 and probably upon Acacia latifolia. 



In my annual report as United States Entomologist for 1886 

 will be found a full characterization of the species in all its stages ; 

 but the three characteristics which most concern the practical 

 man and which make it one of the most difficult species to con- 

 tend with are its ability to survive for long periods without food, 

 to thrive upon a great variety of plants, and to move about 

 throughout most of its life. 



The injuries of this insect, notwithstanding the efforts to check 



