12 BULLETIN 1204, 1". S. DEPARTMENT OF AGRICULTURE. 
Hermione plantation, adjoining the Shirley property, was selected 
as representing a very different type. (See fig. 10.) This property 
is a comparatively narrow strip slightly more than a mile long, ex- 
tending easl ;ind west, bordered on one side by a bayou and on the 
other by small (dumps of timber. This property presented much 
more favorable conditions for low flying than were found on most 
of Shirley, because only a few cabins were present in the fields, 
except a row along the edge of the bayou. It was especially favor- 
able for airplane work in the opportunity offered for straight flights 
a mile long. 
Hermione plantation consists of approximately 1,000 acres. 850 
being cleared and the remainder in timber. The cleared land was 
disl ributed as follows : Cotton "JTo acres, corn 175 acres, peas 10 acres, 
alfalfa 80 acre.-, pasture 20 acres, open hut not cultivated 300 acres. 
LEAFWORM CONDITIONS. 
The Shirley and Hermione properties were both fairly heavily 
infested with the cotton leaf worm during the first generation. A 
very large number of these pupated successfully in the fields, which 
had been practically stripped of foliage by that generation. These 
pupa' matured and the eggs which" were laid by the emerging adults 
began to hatch about August 20. The number of adults became so 
exceedingly great that the infestation of worms which developed 
proved to be one of the heaviest ever noted by the writers. Prac- 
tically every plant had numerous egirs, and as these hatched some 
fields were found to have apparently an average of about 50 worms 
per plant. As the infestation varied somewhat from field to field, 
and eggs were laid in some fields earlier than in others, it was 
necessary to poison the fields at different times. Careful records 
were kept on the worm infestation of each field and the individual 
fields were poisoned as became necessary for the control of the worms. 
Many variations were introduced in the experiments. In some in- 
states the worm infestation was allowed to develop more heavily 
than in others. The operation of the planes was varied to include 
flights at different elevations, at different times of the day. and under 
different air conditions. In addition, some poisons were tested 
merely to study their suitability for distribution from the plane as 
compared with ordinary calcium arsenate. 
BEHAVIOR OF THE DUST IN THE AIR. 
The behavior of the dust in the air was the subject of the first 
studies conducted. In ordinary poisoning of cotton, what has been 
termed the "dust cloud"* method has been developed. The dusting 
machine passing between or over the cotton rows blows out the cal- 
cium arsenate in a fog which penetrates between all portions of 
the rot ton plant, and consequently covers every exposed particle of 
plant tissue. Successful dusting of this type can be done only when 
the air is calm, and it^ success is greatly enhanced by the presence 
of moisture on the cotton leaves. For these reasons ordinary cotton 
dusting has become almost entirely a nocturnal operation, beginning 
usually during the period from 6 to 8 o'clock in the evening and 
continuing in the morning until the dew dries from the leaves, and 
the breeze springs up. which is usually some time between and 8 
