The Milan exchange. (Milan, Gibson County, Tenn.) 1874-1978, 1882-07-29
Injurious Insects.

There are few things more humiliat-
ing to humanity than the sense of man S
helplessness before very small insects
Tigers or wolves we can extermnate
easily enough, if we really set ourselves
to work at Is; rats, mice and weaSels
we can keep down somehow. But be-
fore the Colorado beetle or the seven
teen-year locust we are practically al
most resourceless. And before the
phylloxera or the hop-fly we can hardly
do more than look on regretfuly with
folded hands. Yet it is some consola-
ton to reflect that what seems at first
sight useless and purely ornamental
science can help us to some extent in
dealing with these infinitesimal pests.
The only way to conquer them, if way
there be at all, is to learn their whole
life history; to know them in the egg,
in the .arva, in the pupa, in the full
fedged insect; to crush them in every
stage with whatever weapon the subtle
ties OF chemistry or mere ingenious
brute force can suggest; and to do moth
ing which can in any way give them a
single extra chance of life Nothing, in
fact, could better show the intimate in
teraction and reaction of knowledge and
practice than this interesting study. On
the one hand, no means can be devised
for getting rid of injurious insects ex-
cept by thorough scientific acquaint-
ance with their origin and metamor-
phoses; on the other hand, no such care
full observations on particular life-hiS-
tories have ever been undertak en-. prob
ably, except with the stimulus of some
practical advantage to mankind in view.
Thus science and agriculture both gain
by the conjunction. Even butterfly
hunting has its special commercial uses,
when the butterfly turns out to be the
parent of the gooseberry caterpillar, or
to lay the eggs from which warm sun
will hatch out the destructive cabbage
worm.
Many of these observations help to
bring out the minute interaction which
often obtains between different parts,
OF the organic balance: so that if we
want to exterminate a particular insect,
we must sometimes begin by encourage
ing or REFRESHING some seemingly un-
connected bird or plant. For example
botanists have long known that wet
seasons are particularly favorable to
charlock, and that after two or three
such seasons the fields, unless diligently
weeded, are yellow all over with its
bright blossom. But charock is APP
parently the native food-plant of tur-
nip fly, from which the insect spreads
easily to the cultivated turnip-a close
ly allied artificial form; much as the
Colorado beetle, originally parasitic on
solanum in the Rocky Mountains, took
readily to the richer food of the very
similar potato vines, rs soon as extend
ed tillage began to approach its natural
habitat.
1t is only by such careful observation,
with practical application of the results,
that we can hope to outwit our insect
foes; for the more widely any particular
crop is grown, the more generally can
its natural enemies spread and survive.
Even in England. where hill and dale,
copse and hedge break up the filth, and
where small fields of various staples are
habitually. much internixed the insects
can easily migrate from patch to patch
of their speeialklfood plant: while in
America, where, the same crop, some
times covers hundreds OF square hniles
together on the unfenced and unbroken
plain, locusts and army worms can
march straight across country, day
after day, in regular battalions. ST
James Gazette ~