The Jeffersonian. [volume] (Atlanta, Ga.) 1907-1917, 1910-10-06

In insect life, every destructive in
sect has it's parasite. The latter pur-
sues the former relentlessly, and
numbers it with the things of the
past,
Last year State Entomologist Wor-
sham declared war, under the banner
of the Georgia Experiment Station,
against the red spider. This is a min
ute insect which does much injury
to the cotton leaf The insect attacks
the leaf on the under side and pune
lures it. The spots caused by the
puncture turn brown, and are multi
piled in number till the leaf, stung
all over, falls from the plant. The
red spider, though small, is juicy. It's
enemy, another spider, pounces upon
it after the manner of a cat.
The ichneumon fly is as busy as a
bee during the cotton growing season,
hunting caterpillars and worms that
injure the cotton plant. The fly bores
holes in the body of the caterpillar
and deposits it's eggs therein. The
eggs hatch within the host and the
larvae devour the fatty substance, but
avoid inroads on the vital parts, un-
til fully grown. Meantime the cater
pillar has changed into chrysalis,
with the devouring larvae in it's in
terror. The latter eat the former and,
by and by come out full-1edged flies
to prosecute the mission of their
faithful parents.
Apropose of the boil weevil, Mr..
Samuel Hopkins Adams tells an in
teresting story in the American Mag
azine for July, of the discovery of a
parasite that was induced to prey up
on the boil weevil.
around the cotton fields of the
south grow fringes of ragweed, upon
which breeds species of weevil
closely allied to the destroyer of cot
ton. These harmless Weevils are par
asitized by an ichneumon fly, which
destroys them by laying it's eggs in
the bodies of the young of the weevil.
After sedulously studying the nature
and habits of the fly, the government
entomologists could see no reason
why it shouldn't be induced, under
pressure, to alter it's diet to boil wee
vii A number of the parasites were
raised in captivity, and the choice was
given them of committing race sui
eide or laying their eggs in the boil
weevi1. They chose the weevil. The
eggs Matched, the weevils in the ex-
pertinent station were destroyed, and
there remained only to repeat the ex-
pertinent in the open. Word was
sent to the Texas farmers to cut down
the weeds around the cotton fields az
the proper time of year, viz, just be-
fore the egg-laying time of the para
site fly. Many of them did so. The
problem worked out with mathemati-
cal exactness, as follows: First, the
ragweed being cut down, the habitant
weevils persisted for lack of home and
food. Next, the female parasite fly,
heavy with eggs, sought about for
host to carry and hatch the BROOD
and found all the prospective victims
dead. Only few wing-beats away
stood the cotton rich in weevils. 1t
wasn't the exact species to which the
egg-layer was accustomed, but it
would do at a pinch. So the sur
prised weevils, unable either to es-
cape or resist the fly, found them
selves full of strange eggs and pain
full feelings, and presently died, to
the great profit of the plantatlon
owner. In certain fields about Dali
las. Texas, sixty-three per cent of the
cotton pests were killed in this way,
and in other regions more than SO
per cent. Up to that time the most
effective parasitization had never re-
suited in more than 10 per cent of