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found in my published writings, especially in my report as U. S. Ento- 
mologist for 1891, and it is only necessary to state at this time that 
parasitized puparia of the Hessian Fly were received in large numbers 
and distributed to various points, and placed in the care of competent 
observers in Illinois, Indiana, Michigan, and Canada. The results so 
far have not been marked, and but one positive report as to the accli- 
mation of the parasite has been received, viz, from Prof. S. A. Forbes, 
of Champaign, 111. I am of the opinion, however, that the lack of 
evidence from other points is due almost entirely to lack of proper exam- 
ination, and I have every hope that the species will before long be found 
to have obtained a secure foothold at all of the several points of intro- 
duction. It is a very difficult matter to ascertain the existence of a 
parasite of this minute size, except when it occurs in great numbers. 
It requires an eye trained not only to the examination of these minute 
creatures, but one familiar with the allied imported species and native 
species. The reason for attempting the introduction of this particular 
species was simply that in England it was found to be far more abun- 
dant and far more beneficial than any of our native species have so far 
proved. 
The present year I have become interested in the matter of the 
importation of a predaceous Noctuid {Erastria scitula) which preys upon 
the Black Scale (Lecanium olece) in south Europe and helps materially 
to keep it in check. With the help of Prof. H. Eouzaud, of Montpel- 
lier, France, who has studied the habits of this insect with extreme 
care, I hope to establish it in southern California, where the climatic 
conditions are sufficiently close to those of south Europe, and where 
the Black Scale does great damage to olive orchards and to oleander 
trees, and also affects less seriously the Orange and Lemon. The Black 
Scale has already an important enemy in California in the shape of the 
Dilophogaster above mentioned, but the latter is only two-brooded, and 
the scale insect, multiplying more rapidly, outstrips it in the race for 
maturity. The Erastria, on the contrary, passes through five or six gen- 
erations in the course of a summer, and, as it is purely predaceous, it 
will, I believe, prove a most useful auxiliary against the Black Scale, 
especially if brought over without its parasites. 
So far I have spoken only of the insects which have been imported 
into this country, but some effort has also been made in the opposite 
direction. Thus we have endeavored (and with some success) to return 
the service done us by sending to Australia and New Zealand some of 
our predatory Coleoptera, some of the Pacific coast parasites of the 
Codling Moth, and a species of the interesting genus Baphidia, which 
also preys upon the Codling Moth. 
In 1887 and 1888 the now well-known importation of Vedalia cardi- 
nalis from Australia and New Zealand to California, to prey upon 
leery a purchasi, was successfully carried out. The history of this 
striking example of the beneficial results that may, in exceptional 
