The Dawson news. (Dawson, Ga.) 1889-current, 1923-02-06

Tx large EE-'ox- @ -zsec1 c1SIlics~
I Furrw-1Ve species whscA prey UPON
the boil weerZ are k10wl- OF these.
k2s are uE-as-t.s. wA5cA by means OF
1he1r special organs place eggs on the
/ 5r-arrsar--s stages Of the weevTl within
the square O. b01L The young OF the
pz-zsste devtaop by feeding upon the
I boil vws,eTIls. whach they Ultimately
/ XIII Thus parasites instead OF boil
wesvlIs emerge from the injured frJ1It-
I These enemies of the weevII have ex-
listed N this country Tor an indefinite
tire Their natural habit has been TO
prev rDon weevlls more or less reA7t-
[ ed 10 the boil weeVIl which have been
present III this country for many years.
They never feed upon vegetation.
SINCE tine boil weeyil offered abundant
land favorable opportunities for repro
L ductso-. while their original hosts
were generally NOT very numerous,
they have naturally turned their stten-
t5om 70 the boil weeyil. The weevIl
lmorszIity due TO these parasites IS ex-
iceedIngly variable In many cases no
mortality from parasites is observed,
while on the other hand fields show
| ing from 50 to IS per cent Of the
weeyils killed by parasites are by no
means rare.
The boil weeviI Is attacked by a
number of insects which are not para
sites IN a strict sense but prey upon
| ii as food The most important OF
/ these predatory enemies are ants
| Twelve species are known to attack
the EeeviL They are the minute
brown ants and the yellowish ants
that occur frequently in cotton fields
and are observed running over the
plants or On the ground. Their work
lis not against the adult weeyils, but
, against the immature stages IN the
squares. Some species devote their at
tention principally TO the squares that
have fallen TO the ground, while 9TH
ers habituallyy seek the insects within
/ the squares that remain hanging on
the plants The larvae OF the weevil,
incased In thin covering, offers fOod
that the ants are not inclined TO over
look. They gnaw through the thin
shell inclosing the weeyil larvae, and
the latter IS soon destroyed. In some
cases more than half of the immature
stages in fields have been destroyed
| BY ants alone. To find Is per cent so
destroyed IS not Z rare occurrence.
| Other Factors In Natural Control
Among minor factors in natural
control may be mentioned the devel
opulent OF plant tissue known as pro-
| liberation, which sometimes brushes
the immature weevils; and determin
ate growth OF the cotton (the tenden-
| CIV to cease squaring about the mid
Idle or latter part OF the season.,
which may prevent the development
| OF fall broods of the Weevil. Birds are
| also agents in the destruction OF the
| boil weevil, a fact which has been full
| w treated in the publications OF the
biological survey OF this department.
Variation in Natural Control
Winter killing during Information
and summer killing due TO heat are
lby lar the most important types OF
natural control. If it were not for
these agencies it would be impossible
to raise cotton IN the presence OF the
boil weevil. All control agencies,
however, vary widely from field to
field and season to season in their Ell
Ifect. and this explains the extreme va
ration in the amount OF injury caused
tby the boil weevil. a mild winter fol-
llowed by rainy, cloudy summer ia
vors rapid multiplication OF weevils
anu EAlC AGA4d&E AZ tAAN NOAAOAA NAOPS
lis correspondingly increased, while
the reverse weather conditions may
practically prevent damage 70 the
crop.
/ Dissemination
The boil weevil moves from place
to place by fight Although it IS a
weak flyer compared with many IN
sects, it has been known to cover q
distance OF more than 40 miles IN a
very short time. Its flight can not be
prolonged, but successive short flights
especially in connection with favor
able weather conditions. This IS the
case, however, only during the social
ed dispersion period, which extends
Iron about the middle OF August to
the end OF the season. During the rest
LOT the year the weevil is litte inclln-
ed to fly. There is always a move
ment from fields in all directions IN
search OF alternating quarters in the
Ifall and corresponding movement
iron such quarters to the cotton fields
in the spring. When the insects reach
cotton fields in the spring there is lit
tie further movement until the general
dispersion begins Ordinarily between
the middle OF August and the lst OF
September the weeyil seems to be
seized with the instinct to migrate. 1t
was thought at one time that this
movement was forced by excessive
reproduction and took place only
when all squares and bolls, or the
majority Of them, became infested.
investigations have shown, however,
4that the dispersion takes place ire
ouently when the fields are only
Islightly infested In other words, the
Insect has a well-developed instinct for
extending its range into new territory.
lit is this instinct that has caused the
Iextension OF the infested area in the
limited States year by year. The wee
vii is governed in flight by the wind
LII there is no wind, or only light
one, a. weevil is as likely to fly in one