22 BULLETIN 828, TJ. S. DEPARTMENT OF AGRICULTURE. 
Nine striped beetles were fed constantly on wilted cucumber plants from January 7 
to February 12, 1917. On the latter date all wilted plants were removed from the 
cage (Xo. XXII) and from then until March 10 they were fed on healthy young cucum- 
ber seedlings which were so small that the leaves were entirely consumed. On March 
10 the three beetles left alive were caged with a large potted cucumber plant grown in 
a greenhouse free from wilt. Two weeks later one beetle-gnawed leaf was found 
wilting and after three weeks nearly the whole vine was involved. Bacillus trach- 
eiphilus was isolated from this plant and tested by successful inoculations into 
cucumbers. The cage used for this test was covered both by wire netting and cheese 
cloth, and had not been used for beetles since the preceding fall. 
(Cage XXIV.) From January 11 to February 5, 1917, 25 striped beetles were fed 
on wilted cucumber plants, then all diseased plants were removed and until February 
26 the beetles were fed on very young cucumber seedlings, which were completely 
riddled, as in the preceding test. At the latter date a large potted cucumber plant was 
placed in the cage and left for three days, after which it was removed and held for 
observation. On March 10 this plant was wilted and the vascular system was plugged 
with the typical stringy masses of bacteria. Xo isolations were made from this plant. 
(Cage XVIII.) Wilted cucumber plants from pure-culture inoculations were fed 
to three striped cucumber beetles on January 25, 29, and February 8. All wilted 
plants were removed on February 16 and a healthy young cucumber plant was intro- 
duced. Two days later this plant was removed and a second introduced, and so on 
until the beetles had been allowed successively to feed on four healthy plants. On 
February 19, plant Xo. 1 was starting to wilt around the beetle injuries on one leaf. 
Six days later this plant was showing wilt on several leaves and plant Xo. 3 was start- 
ing to wilt around the gnawed places on several leaves. On March 1, Xos. 1 and 3 
were entirely wilted and Xo. 4 was starting; plant No; 2 showed no signs of wilt. How- 
ever, the leaves on this plant were scarcely gnawed at all by the beetles. Isolations 
were made from plant Xo. 4 on March 1 and inoculations from this source to six cucum- 
ber plants gave typical wilt in every case. 
(Cage XVIII.) On March 20, 1917, a wilted cucumber plant was fed to the same three 
beetles, and on March 28 it was removed and a healthy plant introduced. Two days 
later this was removed and a second one introduced. On April 13, plant Xo. 1 showed 
typical wilt, but Xo. 2 remained free from the disease. 
This last experiment was duplicated on the same date in two other cages (XIII and 
XXI), but in these cases neither of the two plants contracted wilt. 
(Cage XXII.) On the same date (March 20, 1917) wilted cucumber plants from pure- 
culture inoculations were fed to several striped cucumber beetles. On March 28 these 
plants were removed and a healthy plant introduced. Two days later, plant No. 1 
was removed and a second plant introduced. Both plants contracted wilt from the 
beetle injuries and on April 13 were wilted throughout and dying. 
Plant Xo. 2 was allowed to remain in the cage with the beetles. On April 28 the 
plant had long since died, but one beetle was found still alive in the cage and a healthy 
cucumber plant was introduced. On May 7 two leaves had started to wilt next to 
the margins, where they had been slightly gnawed. The beetle had died since the 
last preceding observation. The wilt was a typical case, and the vascular bundles of 
the leaf petioles were filled with bacteria. 
From the results of these " successive infection' ' tests it is demon- 
strated that striped cucumber beetles are sometimes capable of 
successively infecting three or more healthy cucumber plants after 
one initial wilt feeding and that after one such feeding they may in 
some cases in the active state retain their infecting power for over 
three weeks. 
