14 
increase and destructiveness of imported insects, is a temporary one, 
and, to my mind, is largely to be explained by the mental and nervous 
conditions cited at the outset, rather than by external causes. 
Insumming up this phase of the discussion it seems to me that while 
we may normally suffer rather more from insect depredations than the 
Old World, as a result of a more favorable climate, and while the for- 
eign insect enemies coming to us may assume extraordinary powers of 
multiplication and corresponding damage, we have, nevertheless, the 
satisfaction of knowing, in the case of the last at any rate, that ulti- 
mately, and often in a very short time, by the action of the fundamental 
principles noted, the more serious symptoms will disappear and our 
plants will acquire new powers of defense. 
A brief examination of the results of our efforts at control in these 
larger and more general concerns will, I believe, show their general 
impracticability, and will emphasize the wisdom of the laisser-faire or 
let-alone principle of action in such matters. 
In our opening sentences allusion was made to the strenuous efforts 
of the last few years in different countries to prevent the introduction of 
certain noxious insects by the enforcement of inspection and quarantine 
regulations aud in various prohibitions on the freedom of commerce. 
The general impossibility of excluding insects by inspection and treat- 
ment of introduced stock was convincingly shown by Dr. Smith in 
a paper read before the nineteenth annual meeting of the Society for 
the Promotion of Agricultural Science last year in Boston, and this 
point of view has been very strongly impressed upon the writer from the 
outset. To cite anotable example: In 1890 the Department introduced 
some half a hundred small date-palm trees from Egypt and Algeria. 
These proved to be thickly infested with scale insects and were kept at 
the Department under surveillance and treatment for six months, being 
subjected some dozen times to various methods of treatment, and were 
ultimately distributed and planted. In spite, however, of the strenuous 
effort made to destroy the scale insects in question, and the apparent 
absolute freedom of the plants from the presence of the scale when 
sent out, it needed merely a year or two for the scales to develop as 
badly as ever. In fact, on account of the overlapping and clasping of 
the basal part of the leaves of the palm, it proved to be absolutely 
impossible to reach and exterminate the scale secreted there by any 
means whatsoever short of killing the plant. With this same plant 
also a mining insect was found, which lived deeply embedded in the 
thick part of the plant, absolutely beyond the reach of any gas or wash 
or of any possible treatment. 
The experience cited has been duplicated many times with introduced 
stock, and is not a novel one by anymeans. Take a carload of plants, 
consisting of thousands of trees and shrubs, such as was recently 
received by the Department of Agriculture from Japan; no amount of 
inspection, even if conducted by an assemblage of all the recognized 
