132 
feet in height, and treated with arsenate of lead, are comparable 
with twelve trees, all less than thirty feet high, left untreated as a 
check. The treated trees were sprayed twice, once May 23 and 
again June 6. Ten were sprayed with the arsenate of lead of the 
strength usual in orchard practice — 12^^ ounces of sugar of lead 
and 5 ounces of arsenate of soda, dissolved in 50 gallons of water. 
Five of the trees were sprayed with a solution of twice this strength, 
the solid ingredients being dissolved in 25 gallons of water. All 
twigs which fell from these various lots, both checks and experi- 
mental trees, were gathered and counted daily, with the general re- 
sult that the check trees dropped in all 1148 twigs, or an average of 
96 per tree ; those treated with the weaker spray dropped 420 twigs, 
an average of 43 per tree ; and those treated with the stronger spray 
dropped 65 twigs, — an average of 13 per tree. In other words, the 
weaker spray preserved 55 per cent, of the twigs which would 
otherwise ha\'e fallen, and the stronger spray, 85 per cent. 
Only one of the largest trees was sprayed under conditions to 
serve the purposes of an experiment. This tree was about seventy- 
five feet high, and from it fell only 95 twigs in all, while eight un- 
treated trees, averaging sixty-four feet in height, gave a total of 
12,721 fallen twigs, an average of 1490 per tree. The number 
varied under the different trees from 937 to 2029. The ratio of 
benefit on this large tree thus seems to have been 94 per cent. Ex- 
cept for the difficulty and labor of spraying large shade trees, this 
insecticide treatment was as satisfactory as could be expected of any 
like operation. 
When the insecticide was first applied there was 1)ut little wind, 
and the weather was fair. A heavy rain with wind followed the 
second s])raying, and doubtless diminished somewhat its effect. 
Twigs fell in considerable numbers until the 28th of June, after 
which but few were collected. 
In preparing the arsenate of lead, the sugar of lead and the 
arsenate of soda are separately dissolved, and poured, in succes- 
sion, into a quantity of water sufficient to reduce the solutions to 
the strength desired. In the Decatur experiment a Morrill and 
Morley "Eclipse" hand-pump No. 6 was used, witli two 35-foot 
lengths of hose and 12-foot extension poles. A 14-foot step-ladder 
was sufficient to give access to the tops of trees of medium size, 
while for those from sixt^' to eighty feet high, 65-foot extension 
ladders were used — the property of the Decatur Fire Department. 
The amount of the insecticide required, varied from five to ten gal- 
lons for the small and medium trees to forty gallons for the largest 
