718 HINTS FOR THE PROMOTION OF ECONOMIC ENTOMOLOGY. 
The last portion of our subject yet remains to be discussed : 
the practical application of the great mass of scientific truth 
which has been thus far gathered in relation to the structure, 
classification, habits and life history of insects. 
Of the immense,number of insects which are found in any given 
portion of the earth’s surface, comparatively few are capable of 
becoming so numerous as to affect plants injuriously. But from 
time to time, the interference of man in the progress of civiliza- 
tion destroys the balance which previously existed, and insects, 
before unimportant by reason of their comparatively small 
numbers, finding the checks to their increase removed, suddenly 
become very destructive to one or another of our agricultural 
products. In this case what is to be done? Obviously there are 
but two courses; the first to abandon the crop, until the insect 
enemy is reduced by starvation to its former insignificance ; the 
other is to establish, by human intelligence, a system of checks 
to take the place of the divine machinery which has been inter- 
fered with by the same human intelligence. The second is the 
course that is, and probably will continue to be, generally adopted. 
This new system of checks, according to the habits of the insect 
to be suppressed, may be divided into (1) those requiring per- 
sonal labor and diligence alone; (2) personal labor assisted by 
contrivances ; (3) automatic contrivances, not requiring personal 
attention (including the use of poisons); (4) the production of 
diseases ; (5) the introduction of parasites and other enemies. 
Under the 1st head may be mentioned the destruction of larvae 
of borers by wires, etc.; 2nd, the collecting of plum weevils, 
tato chrysomele, etc., by large nets, and their subsequent de- 
struction; 3rd, sugaring with poisoned food, specially applicable 
to nocturnal lepidoptera, and the use of fires, or lanterns with 
a vessel of poison, to attract nocturnal species ; 4th, the commun- 
ication of fungoid disease (like pebrine, which affects the silk- 
worm) to other lepidopterous larve;* 5th, introduction and 
preservation of insectivorous mammals, birds, reptiles and insects 
ing their types in my collection, I hereby pledge myself that my collection shall never 
be sold or divided, but that it shall be placed permanently, where it can be best cared 
for, and mad ible for the authenticati specimens. And I invite those who 
are willing to sacrifice rarities, or even uniques in their collections for such a ‘purpose, 
to send ; Sth tha fnil aa aero are th ee g th m of more 
general use than they can be in local collections. 
* I am extremely hopeful of the result of using this method. I have learned of an 
piso = ae pe ae row oe £ +} as ; ilkkworms, the whole 
OY sume 
sana Aj 
of the caterpillars in a nine-acre piece of woods were destroyed. 
