, 1912-09-21

charge of the southern field crop insect In
~vestigations of the Bureau of Entomology OF
the United States Department of Agriculture,
was endeavo uring to account for the unusual
occurrence of this insect on the theory that
it had invaded the S )uthern States by mi
grafton from Mexico and perhaps also from
the West Indies.
At a meeting of the American Association
of Economic Entomologists at Washington.
d. c., IN December last, Mr.. Hunter read a
paper on the outbreak of Al hama arglWdce0
in 1911. Which has been published IN the
JouW0I Of Ecoa00eic Entomot0gy, Vol. V,
D.. 123. The following items are ahstracted
from Mr.. Hunters paper and tue report of
the discussion which followed its reading.
For nearly a quarter of a century there
has been no serious outbreak OF the cotton
worm in the cotton belt Of Tie United States
until 1911, aud as a result many planters
were not familiar with this insect. The re-
serve stocks Of Paris green and other arse
meals throughout the South had become
much reduced, and when the outbreak of the
cotton worm became general the demand for
arsenica,s became very great, many OF the
lrger factories in different parts of the coun-
try rnnning nigh and day.
The earliest seasonal record for this insect
in 1911 was received from Brownsville, Tex
as, which is on the Mexican border, and at
two nearby points in Mexico. As early MS
June 10, the greater number of cotton fields
in this d strict were almost entirely stripped
of their foliage. In Louisiana and MIssls-
sippi, defoliltion of cotton fields began to be
reported about the middle Of July. In the
eastern part of the cotton belt, this condI-
ton was observed in August and September.
1t is concluded that the outbreak OF 1911
started from two infestations, one apparently
unimportant, in the eastern part OF the cot
ton belt, another of greater importance in
southern Texas, which began in Mexlco, bnt
it does not seem that the occurrence of the
cotton worm throughout the cotton belt
could be explained on the theory that these
two infestutions had spread aud eventually
coalescel. At widely separated points eX-
tending far to- the north Of The latitude IN
which this insect breeds. large swarms OF
cotton moths appeared almost simultaneously
between September 10 and October y. 1t
is stated that the occurrence OF these enor-
NOUS numbers of moths toward the end OF
tho season and the rapid increase OF tAe
caterpillar shortly before that time were due
to invasion Of mot his from SO tn America
through Mexico or over the Gulf OF Mexico.
Rather complete and full records exist Of
the depredutions Of the cotton worm from
1893 to 1891. These contrast strongly With
the meag:e accounts OF this insect III more
recent years, when by the use Of arsehicaI
insecticides and changed plantation methods
the effects of cotton worm attacks have been
much modified.
In 1916 the theory was advanced that
severe attacks of the cotton worm occurred
once in twenty-one years. The records show
that in the years 1888, 1904, 1926, 1916, 1868,
1890, and 1911 there have been severe and
general outbreaks of this insect, while in
other years the attacks have often been So
we're in localities but not general throughout
the cotton belt, with the exception of one
that occurred in 1928. Two of the periods
indicated by the figures given are Of twenty
two years while the others, it Will be obsorv-
ed, are of twenty-one years each.
Another point of interest which was
brought out in the discussion of Mr.. Hunt
er's paper had to do with the food plant of
the cotton worm, and its native home. So
far as is known at the present time, the only
food plant of the cotton worm is cotton, aud
it is not believed that this insect can live
aud go through its developmental changes
to maturity on any other plant. 1t is known