246 
JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 16 
A part of the grove was bordered by pastures, and a tall double row 
of maples formed a difficult hazard at one end. 
A moderate infestation of the first brood of the catalpa sphinx was 
present and when the work was done the larvae were but % grown. 
At least 4 /5 of the foliage was present, hence the leaf canopy was very 
dense. 
Object of the Test 
The problem was two fold. 1st: To determine if a single application 
directed against the first brood larvae would control the insect for the 
season. 2nd: To determine if the heavy leaf canopy would be pene¬ 
trated by the dust cloud. 
Details of Applying the Dust 
The McCook landing field, 20 miles away, was used as a base to 
operate from. The applications were made June 15 with a gentle wind 
blowing 2 to 5 miles an hour almost lengthwise of the grove, the flights 
for the most part being made almost directly into the wind, and at an 
altitude of 40 to 50 feet directly above the trees. 
Because of the height of flight and the narrowness of the grove it was 
estimated that only about one-half of the 200 lbs. of powder used was 
deposited on the trees. 
An excellent distribution of the poison was procured except in the im¬ 
mediate vicinity of the bordering rows of tall maples and at the opposite 
end where the hopper was “cut off” too soon in order to prevent the dust 
falling on the pasture land. 
However, with all our care, some poison fell on the pastures but it was 
found to be comparatively easy to remove this where the grass was short, 
by dragging over it a small, many branched tree. Where the grass was 
tall, we dragged over it a thirty foot pole with a heavy log chain looped 
behind. Both plans jarred the poison from the grass blades and de¬ 
posited it on the ground beyond the reach of stock. 
The Effect on the Caterpillars 
The first ailing caterpillar was found 8 hours after the first charge of 
powder had been released and by 46 to 50 hours after the application of 
the poison the dead caterpillars were very abundant. 
In brief the test was very successful—it destroyed the first brood of 
worms and prevented the appearance of a destructive second brood and 
effected a satisfactory commercial control of an outbreak of the catalpa 
