THE PECAN LEAF CASE-BEARER. 25 
sulphuric acid, and 2 fluid ounces of water should be used to each 
100 cubic feet of space inclosed. In purchasing sodium cyanid 
it is essential to obtain a high-grade product, 96 to 98 per cent pure, 
or, in other words, one that contains not less than 51 per cent of 
cyanogen. Commercial sulphuric acid, specific gravity 1.84 (66° 
Baume), which is approximately 93 per cent pure, should be used 
for fumigation in order to obtain the best results. 
SUMMARY. 
Although the pecan leaf case-bearer is preyed upon by a number 
of parasitic insects and several species of birds, it was found during 
a course of studies extending over a period of three years that 
neither the parasites nor any other natural checks could be relied 
upon to control it, but that certain artificial measures were suc- 
cessful. 
It was found impossible successfully to control the pecan leaf 
case-bearer during the dormant season, at which time the larvae 
were in hibernacula around the buds. Of the various spray materials 
tried for the destruction of hibernating larvae, commercial lime- 
sulphur solution at the strength of 1 : 8 and 1 : 10 gave the best 
results, but this method failed to destroy a sufficient number of 
the larvae to justify its use. Tests with miscible oils at 1 : 12, 
1 : 15, 1 : 18, and 1 : 20, and 10 and 20 per cent kerosene emul- 
sions applied during the dormant season were found to be ineffective. 
Because of the manner in which the larvae feed upon the buds 
and foliage, the pecan leaf case-bearer in the active larva stage 
during the spring was not satisfactorily controlled. Spraying ex- 
periments, using a single application of arsenate of lead (paste) at 
3 pounds to 50 gallons of water, 40 per cent nicotine sulphate at 
1 : 700, and commercial lime-sulphur solution at 1 : 40, were tried 
on orchard pecan trees as the larvae emerged from their hibernacula, 
at which time the buds were beginning to unfold, but none of these 
materials proved effective. Two applications of arsenate of lead 
(paste) at 3 pounds to 50 gallons of water were made on large pecan 
trees, the first as the larvae emerged from their winter cases and the 
second eight days later. This treatment destroyed many larvae but 
was not entirely effective. 
Experiments in spraying with certain strengths of lead arsenate, 
conducted during the summer (August), gave very satisfactory 
results in the control of this pest, as it was discovered that the 
young larvae might be destroyed readily at this stage. Based on a 
large series of dosage tests with lead arsenate, conducted on orchard 
pecan trees, it was found that no strength weaker than 1 pound of 
the powdered form or 2 pounds of the paste to 50 gallons of water 
