8 BULLETIN 1102, U. S. DEPARTMENT OF AGRICULTURE. 
SUPPLEMENTARY EXPERIMENT. 
On September 15, 1921, 12 clusters of Curtis nuts were brought 
into the laboratory and placed in lantern-globe cages. Short stems 
were left on the clusters which were inserted in bottles containing 1 
water. Each cage had a strip of cheesecloth tied over its top. 
From five to seven specimens of adult southern stinkbugs were 
placed in each of six of these cages. The other six clusters were 
reserved as checks, 
but were subjected 
to the same condi- 
tions, except that no 
bugs were confined 
with them. 
On September 18, 
or approximately 65 
hours later, all the 
nuts were opened and 
examined. Of the 
17 nuts confined with 
bugs, each had from 1 
to 12 typical kernel 
spots. Of the checks, 
numbering 15, not the 
slightest evidence of 
kernel-spot was found 
on any. Cultures 
were made on beef 
agar from 10 spotted 
nuts of the first series. 
Xo growth of any 
kind w a s produced 
from these cultures. 
This test alone would seem to prove that pecan kernel-spot is 
caused directly by the stinkbugs feeding upon the kernels or by in- 
jecting toxic substances into the tissues. It also indicates very 
strongly that the Xezara bugs do not regularly transmit parasitic 
microorganisms to the pecan kernels with their piercing mouth 
parts. 
LABORATORY CULTURES OF KERNEL-SPOT. 
Owing to the porous structure of the kernel-spots and their tend- 
ency to quickly absorb liquids, the method of soaking diseased 
plant tissues in a solution of mercuric chlorid in preparation for 
making cultures was found to be impracticable. The following 
method was used, giving very satisfactory results : 
Fig. 5. — Southern stinkbugs {Nezara viridula) on pecan 
nuts of the Curtis variety. (Natural size.) 
